It’s simple but effective advice.

There’s mounting evidence that spending your time with good, supportive friends who have similar long-term goals as you is one of the best (and face it, most fun) ways to live longer and healthier.

The evidence takes many forms

People run faster and longer if they see their friend went out for a run that day or the day before. Strong friendships are as effective as exercising and quitting smoking when it comes to increasing your life span. A good relationship can even boost your metabolism. There are more studies, but they all come to basically the same conclusion: Solid bonds will make you a healthier person.

(This doesn’t mean you should ditch your friends going though a rough patch)

Nor should you discriminate against people dealing with mental illness. Instead, keep an eye out for toxic people, learn the signs of an expired friendship, and don’t feel guilty about breaking up with friends you’ve known forever.

And if you’re freaking out about not having enough happy and healthy friends, consider being the agent of change in your own friend group. Or if it’s a matter of getting new friends together, own that and put in the work. Clearly, it will be worth it.