11 things to master before you turn 40

Negotiating

If the thought of getting into a debate with your boss over how much money you deserve makes you nauseated, you're not alone. It helps to both research and practice, as much as you can stand.

If you're negotiating your salary, the best strategy both for getting what you want and still coming off as friendly is to ask for a range including and above your target number. For example, if you're aiming for a $100,000 salary, you'd suggest a $100,000 to $120,000 salary.

Another trick is to frame your proposal in terms of what you're giving the other person as opposed to what they're losing. So instead of saying, "I want $10,000 for my car," you'd say, "I'll give you my car for $10,000."

Establishing a regular sleep schedule

We know it's hard to hear, but it's helpful to wake up at the same time every day — even on weekends. If you oversleep for even a few days, experts say you risk resetting your body clock to a different cycle, so you'll start getting tired later in the day.

On a related note: Experts also advise against hitting "snooze" and going back to sleep when your alarm goes off in the morning. Instead, hit the snooze button once and use the time until your alarm goes off again to turn on a lamp and do some light stretching.

Making small talk at parties

Chances are good that, if you're feeling awkward about chatting with a bunch of impressive people you've never met, other people are feeling the same way.

But as Marjorie Gubelmann, CEO of Vie Luxe, told Oprah.com: "Even if you won't know anyone and you're feeling intimidated, you must go. Do not stay home. So many people are afraid that no one will talk to them and they'll leave feeling awful — but has that ever happened to you?"

One solid way to improve your small-talk skills — and alleviate some of the pressure you feel — is simply to demonstrate interest in your conversation partner. Ask the person questions, let them talk about themselves, and allow them to teach you something.

Finding and sticking to an exercise routine you enjoy

A professor of behavioral medicine told The New York Times that research suggests people who dislike or feel inept at their workouts are unlikely to continue. So experiment and find an activity you really love, whether that's spinning, Zumba, or weightlifting.

Remember: In your 30s, you start losing muscle mass, so it's especially important to exercise at this time.

Finding your career 'sweet spot'

Brian Fetherstonhaugh, worldwide chief talent officer at The Ogilvy Group, writes on TIME.com: "Your career sweet spot is the intersection of three things: what you’re good at, what you love to do, and what the world values."

He says you should "use your 30s to test out hypotheses," like whether you're skilled enough in one area to make a career of it.

Saving for retirement

Your golden years are inching ever closer — and you'll want to be prepared to enjoy them.

As Business Insider's Lauren Lyons Cole reported, by the time you're 40, you should have saved about three times your annual salary.

Investing your money can grow your savings exponentially — without you having to do much of anything. In fact, Lyons Cole, who is a CFP, reported that "missing out on stock market growth spurts is actually riskier than not investing at all."

Investing in relationships

On a Reddit thread about lingering regrets people have from their 30s, multiple people posted about not spending enough time with their family.

For example, mustlovecash writes that they regret "not spending more time with my parents - walking, talking, travelling - while they were still young enough to actively enjoy it" and "ever, ever choosing work time or personal time over spending time with my wife and children. Children grow quickly, and leave home quickly, and the spouse who remains with you will again become the closest and most important person in your life."

Indeed, according to the Harvard Study of Adult Development, good relationships keep us not only happy, but healthy as well. Interestingly, the study found that quality of relationships is more meaningful than quantity once you hit 30.

Saying 'no' to people

There's an entire Quora thread dedicated to learning how to say "no," where Eva Glasrud writes, "we routinely overestimate the cost of saying 'no.'"

According to Glasrud, the best way to muster up the confidence to turn down a request is to recognize that "[t]here are some things you can never have back. Your time, your health, your virtue, your life.

"Don't mess around with those things. It's fine for people to ask — most likely, in their mind, they're trying to help introduce you to a great person or opportunity or meaningful cause. And it's just as fine for you to say 'no.'"

In some cases, you can even say "no" to your boss — sort of. According to national workplace expert Lynn Taylor, if your boss presents you with a new assignment and you're already overloaded, you might respond with:

"I would be happy to do that project, but what that could mean is that [whatever other project you're working on] will have to be put off until tomorrow, because I was actually going to spend the next three hours finishing that proposal. Would you like me to put that off?"

Keeping a clutter-free home

If you're looking to start de-cluttering, there's a whole movement to support you, inspired by Marie Kondo's "The Life-Changing Magic of Tidying Up." The process starts with a tidying "marathon," in which you keep only those items that "spark joy" — and get rid of everything else.

As Business Insider's Erin Brodwin reported, clutter can be a source of stress for some individuals and families. Then again, people tend to be more creative in messy environments — so if you aren't feeling motivated to re-organize your entire office space this second, that's probably okay, too.

Practicing hobbies

Writing on Quora, Vishwa Sharan advises 30-somethings to develop hobbies. People "forget that there is a beautiful life outside of their work," Sharan says, and it's important to find non-work activities you can pursue for the rest of your life.

If you're looking for ideas, Business Insider's Rachel Gillett put together a list of 15 hobbies successful people practice in their spare time, from bridge (Bill Gates) to playing the ukulele (Warren Buffett).

Making new friends

In case you haven't heard, it's not so easy to find BFFs once you're off a college campus. That doesn't mean it's impossible — in fact, there are plenty of science-backed strategies for forging friendships in adulthood.

One way is simply to do activities you enjoy so that you meet a steady stream of people with similar interests. Another way is to make yourself a little bit vulnerable: Exchanging confidences as a relationship progresses can make two people feel closer.

As the late psychoanalyst Hedda Bolgar told Oprah.com when she was 103 years old and still practicing: "It's important to be part of a community!"