Sometimes it can be hard to look on the bright side of life—and those are the times when it might be most important to do so.A recent research paper published online in September 2013 in a journal of the American Heart Association shows that even for people dealing with heart disease—the number one killer of adults in this country—a positive outlook means living longer and stronger, or as we say, living younger.The study, which looked at 607 patients in a hospital in Denmark, found that patients whose moods were overall more positive were 58 percent more likely to live at least another five years. These people exercised more, too. The scientists can’t say for sure if positivity led to exercise or if exercise improved mood, but we say that the important message is the same either way: Positive thinking and regular physical activity are really important for life (and beauty, too).MORE: Positivity Is the Best MedicineOne of the reasons we love this study so much is that we’ve been saying this the whole time! Having the right attitude is even more important for your body than daily sunscreen and a weekend spa getaway, every other week—yes, that important. Humor improves immune cell function, helps you ward off illness and decreases your chances of cancer—and apparently also increases your chance of living after heart disease hits. Not bad! (We’d rather you change your exercise, food and stress management programs now so heart disease is unlikely in the first place).And the chicken-or-egg thing doesn’t bother us at all. Physical activity improves mood, so if working out makes you feel better, that’s great. It does us. The other side of this two-headed coin is that feeling happier and more optimistic helps motivate you to engage in healthful habits. That might mean a hike in the woods, hopping on a treadmill, eating more vegetables or all of the above. It’s a win-win as we see it.How to Get on the Positive TrackIt’s not like you can go to your doctor and get a prescription for positivity. (What would it say, “Tell two jokes every 4 to 6 hours”?) You have to take the initiative to inject humor into your life. There are some obvious ways and some less obvious ways. First, the obvious ones. TiVo Letterman and the Daily Show (because sleep is important for health, too), read a blog that makes you laugh, or hang out with friends who never fail to boost your mood, no matter how much of a sourpuss you’ve been. Go to the park with your dog, play dress up with your kids; anything that’s going to bring a smile to your face is good medicine.MORE: How to Express GratitudeSome less obvious choices? Studies have shown that helping others helps you, too. Volunteering is a great way to give as much as you get and get as much as you give. Practice gratitude, which means thinking of, or writing down the things that you are grateful for in your life. Positive affirmations remind you of the wonderful things in your life and make you feel happier and more satisfied.It’s a positive cycle: The more you do it, the easier it gets—and the younger you’ll feel and look.