How much you have to exercise and what kind of workout to do to get different types of benefits

Even small amounts of exercise can make a big difference long-term — running five minutes a day could add years to your life, if you do it for years.

You can get big benefits without having to do a lot: running just five minutes per day could add years to your life, according to a study in the Journal of the American College of Cardiology.

To be clear, you'll probably want to exercise more than this. But it's worth knowing that even just a little exercise is far better than none.

This study found that over a 15-year period, people who ran just a few times a week (averaging out to five minutes a day) had about a 30% lower risk of death than people who didn't run at all. And people who ran more had even healthier hearts.

For a mood boost, 30 minutes of aerobic exercise is enough to make a difference.

Spending 30 minutes on a treadmill is enough to lift someone's mood, according to a study published in the journal of the American College of Sports Medicine. Even participants who moved at a walking pace received the same mood-lifting benefit.

This shows that no matter what pace you're going, moving has positive effect, adding to the already significant body of research showing that running and other forms of exercise can improve mood and help fight depression.

In another study, women who did three 50-minute aerobic classes a week had significantly improved mood, decreased anxiety, and were more optimistic after 12 weeks.

To lift symptoms of depression, that mood boost is a good start. But keeping up a regular exercise routine is most effective for improved mental health, no matter what type of workout you do.

In one pilot study, participants got 30 minutes of aerobic exercise a day for 10 days straight, and showed significant improvement in depression symptoms by the end of the study.

Other studies have compared aerobic exercise to resistance training programs to see if one worked better for treating depression.

The overall verdict from one major review of studies found that either sort of activity could be equally beneficial. Sample training programs from several of those studies had participants engage in either strength training or aerobic exercise at least three times a week, 60 minutes each time, for 12 weeks.

To meet basic fitness guidelines, cut your risk for death and chronic disease, and improve mental health, exercise at least 30 minutes a day.

According to a new CDC report, only 22.9% of Americans aged 18 to 64 met the government's recommended physical activity guidelines between 2010 and 2015. Those guidelines call for healthy adults to do a minimum of two and half hours of moderate intensity activity — or 75 minutes of vigorous intensity activity — plus at least two muscle-strengthening days a week.

To meet the CDC's bare minimum, you can put in about 30 minutes a day. Five days of moderate intensity aerobic exercise — a 30-minute brisk walk or a casual bike ride — is enough to meet the aerobic guidelines. Then two days of resistance training, using weights or bodyweight exercises, is also important, as these activities are the most important things you can to strengthen bones and muscles.

If that sounds like a lot, you can still get things done faster. It takes just 75 minutes of vigorous exercise to meet weekly guidelines. This could be a good paced run or swim — anything that gets your heart pumping.

Research by the American Heart Association verifies that doing at least this much is enough to lower risk of heart disease.

But if you want to counteract the effects of sitting a lot, you want to get at least an hour of exercise in each day.

Sitting all day basically causes gradual damage to your heart, according to recent research.

While meeting the basic fitness guidelines is important, most studies show that isn't enough to offset the harms of sitting. To do that, you essentially need to double the recommendations, getting between 60 and 75 minutes of moderate intensity aerobic exercise a day.

Doing at least two days of strength training exercises is still important, too.

To improve at any particular aspect of fitness, try to get a real workout in at least three days a week.

At the very start of a strength training program, some people see significant improvement working out two days a week, Shawn Arent, director of the Center for Health and Human Performance at Rutgers University and a Fellow in the American College of Sports Medicine, told Business Insider. But most research shows that to really improve aerobic fitness or strength, people need to work out at least three times a week.

Ideally, you should do something fitness-related every day, since inactivity is a real killer. But whether you're trying to get stronger or build up aerobic fitness, you want to work towards those goals at least three times a week, and maybe more.

If you're doing a short interval training workout — something like a high-intensity 7-to-10 minute circuit — you should be doing it three-to-five times a week to see results.

Though short workouts can be effective, you still have to do them enough that your body is regularly stimulated and your muscles grow.

For quick interval circuits like the popular 7-minute workout, that means doing them a minimum of three to five times a week, the exercise physiologist who came up with that workout told Business Insider.

And even though these sorts of workouts can help you fit exercise in when you're busy, it's best if you're spending more than just a few minutes a day being active.

People's muscles start to get stronger and better at contracting within a few weeks after starting a new program.

It doesn't take long for your body to start to change if you start working out.

Within a week of starting an exercise program, mitochondria, the energy factories for cells, start to multiply, which provides more fuel for your muscles.

"After two to four weeks your nervous system is much more efficient at being able to contract your muscles," Robert Newton, director of Edith Cowan University's Exercise Medicine Research Institute, recently told Australia's Nine News.

Within 6-8 weeks, you may have 50% more mitochondria, which helps provide more endurance.

Give yourself 8 to 9 weeks to train for your first 5k race.

A 5-kilometer (3.1 mile) race is an accomplishable goal for most people.

Most beginner starting plans say that runners can go from being total couch potatoes to running a 5k in nine weeks, training 30 minutes at a time, three times a week.

If you're already in good shape, more specialized training programs can help you hit an ambitious time goal within eight weeks.

To significantly improve strength, endurance, or visible muscle definition, give yourself 12-16 weeks.

Exercise is progressive, and — depending on your starting fitness and age — you may be able to see steady improvements for years. But if you're starting a new fitness program or trying to prepare for a specific competition, you should give yourself 12-16 weeks to really make meaningful progress, according to Shawn Arent, director of the Center for Health and Human Performance at Rutgers University and a Fellow in the American College of Sports Medicine.

It's not that you won't see improvement soone. But 12 to 16 weeks is the amount of time most exercise scientists say you should give yourself to see significant improvement from any one training program.

If you can make it six months, you're most likely to stick with a training regimen.

During the first 6 months, many exercise programs see a 50% dropoff rate. But after this point, people are more likely to stick with a program.

As your body adapts, you see results, and you grow to appreciate the mood boost that comes from exercise, it'll get harder and harder to skip a workout.

High intensity interval training is probably the fastest way to improve peak fitness, with 12-to-16 week HIIT programs often showing improvements equal to or better than those from traditional workouts.

High intensity interval training involves workouts that alternate bursts of activity at close to maximum possible intensity with periods of rest.

Various studies show these programs are an excellent way to improve the body's ability to use oxygen, often considered a benchmark for overall fitness. They also have strong effects on blood pressure and fat-burning capacity.

Even a minute of full intensity training can improve the aspects of health. In one small study published in 2016, researchers had a group of men do workouts consisting of three 20-second bursts of all-out exertion, with some warm-up, cool-down, and rest in between sets. The results suggested those participants' fitness levels improved as much as those of men who worked out for 45 minutes at moderate intensity.

Most high intensity workouts are of slightly longer duration (between a minute and three minutes), and research shows these are often the most effective ways to improve VO2Max, blood sugar levels, and more.

If you want to get strong quickly, a high intensity training program can improve strength within three to six weeks.

A recent study by the American Council on Exercise compared two small groups of men and women, enrolling them in either a more traditional strength training program or a type of high intensity interval strength training program.

In the regular program, participants lifted at 60-70% of max weight for more repetitions. In the high intensity program, participants lifted 100% their of max weight for fewer reps.

After six weeks, participants in both groups were significantly more fit. But participants in the high intensity training got stronger faster, showing improvement within three weeks in some cases — and only spent half as much time working out.

There's some evidence that to protect the brain from aging, regular moderate intensity aerobic exercise at least four days a week may be best.

Researchers have found that older adults with mild cognitive impairment who begin a program of walking 30 minutes a day at least four days a week for 12 weeks show strengthened connections in areas of the brain associated with memory. There's also animal research showing that endurance workouts (the equivalent of distance running) are associated with the development of new nerve cells in the brain.

This research indicates that endurance aerobic exercise is more beneficial for neurogenesis than strength training or high intensity interval training. Other researchers have found that adults who engage in aerobic exercise show increased brain volume in areas connected to memory.

Nine months into cardio training, your body should be significantly more able to make use of oxygen.

If you've been focused on cardio training, like distance running or swimming, your body's VO2max, or ability to make use of oxygen, should have increased about 25% by now. It's possible you could see even more improvement if you incorporate interval workouts into your program.

To improve bone health, keep up with strength training for at least six to 12 months.

At some point after age 30, we begin to lose muscle mass and bone density. By building up strength, you can delay and even reverse the loss of bone density and muscle mass that come with getting older, according to Arent.

It can take time for your skeleton to really start to adapt, potentially up to a year. Within that amount of time, some research shows it's possible to actually reverse the effects of osteoporosis with regular resistance training. But by that time muscles will have grown, endurance will have improved, heart function will be better, and bones will be getting stronger.

To sum it all up, just do whatever it takes to make fitness a lifelong habit.

To hit minimum fitness guidelines for aerobic exercise and resistance training, do something every day, every even if it's a moderate intensity brisk walk. Those walks can be enough to meet minimum aerobic workout guidelines or can be a good recovery day if you are going harder other days.

On days where you don't have a lot of time, know that it's still possible to make significant progress with a short, intense workout.

But there are benefits to working out for longer periods of time too, which can help you burn more calories and might be beneficial for brain health.

If you really want to improve at something, do it at least three days a week.

Finally, turn fitness into a lifelong habit, as the longer you do it, the more benefits you will see.