You can still get in shape even if you don't have much time to work out - these are the best workouts to do if you only have 20 minutes

According to Barone, there's no one best workout, and for many people, picking a few workouts might be the easiest way to stay interested enough to work out once or twice per week.

Most short workouts will be based on the ideas of high-intensity interval training, though some call more for sustained activity throughout.

High-intensity interval programs involve a warm up, followed by a few cycles of intense activity with short rest breaks in between. That activity could be sprinting, swimming, cycling, or body-weight exercises.

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.

To try this routine, do a two or three minute warmup. Sprint or cycle at full intensity for 20 seconds, then take it easy for two minutes. Repeat the sprint twice more, and then cool down for a few minutes after your third sprint. That's a 10-minute workout.

If you'd prefer a balanced full-body routine that can be done quickly, the Johnson & Johnson Official 7 Minute Workout can provide both aerobic fitness and muscle strengthening.

Using the free version of the fitness app Sworkit, you can choose the type of workout you want, pick the amount of time you want to work out for, and then follow along with the playlist of exercises that are demonstrated on screen throughout the workout.

If you want to stay strong as you age and your body starts to decline, two exercises are essential, Michael Joyner, a physician and Mayo Clinic researcher who is one of the world's top experts on fitness and human performance, previously told Business Insider.

They are burpees and jumping rope.

These exercises work your whole body and can help you build both strength and endurance at once. "On hard days, I'll sometimes alternate a minute of burpees with sets using a weighted jump rope," Joyner told Business Insider. Ouch.

One study published in the Journal of the American College of Cardiology found that running just five minutes a day could add years to your life and provide the same health benefits as running much more.

Running is an easy way to get intense exercise, even if you aren't a particularly fast runner. At least in that study, which followed a group of 55,137 adults for 15 years, people who ran just a little had reduced rates of cardiovascular disease when compared with non-runners, rates comparable to those in people who ran a lot.

Short workouts can make it a lot easier to hit your weekly fitness goals. But building in some moderate activity during the day can help, too.

Researchers have found that the best way to counteract the effects of the sedentary lifestyles many of us lead isn't necessarily with vigorous exercise. Getting up to move around every so often can make a huge difference — just try not to stay seated for hours.

Throughout the day, get up and go for a stroll, ideally for at least a couple minutes every half hour. Ideally, you should try to spend two hours out of your seat on a workday.

Walking counts as moderate exercise, too. So try a few walking meetings or phone calls. And try walking short distances instead of taking a car. You'll steadily chip away at your fitness goals, and feel a lot better for it.