Sex
Getting laid helps prevent a man from going bitter. We all know that's not a secret. Unless he's asexual, men need sex, not masturbation, in order to stay happy. No one likes to keep getting rejected for something they really want. Pleasure, especially sexual pleasure, makes people happy.
Bromances
Friends give people company and happiness. Guy friends can relate to them the most. They feel more comfortable around guy friends because there is no pressure to act a certain way. There are certain things they can bond over with their guy friends.
Family
Having a good father figure and being happy whenever he's around his relatives can also prevent a man from going bitter. His family doesn't stress him out or make him upset/annoy him in any way.
Stability
What I mean by this is having a stable job and/or getting good grades, having a good reputation in school or at work, and generally having a stress free life. A man who has his life together is more likely to be a happier man than a man who has a poor life.
Exercise
Men who exercise are more attractive than those who don't. This will help them with getting laid more. Exercise also helps people become happier.
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