It's complicated, but basically... learn philosophy, learn to understand your desires and thereby justify your existence. You can start by thinking of how the universe might have originated, how it works and how you originated.
It is difficult, but it's doable. If you have the time, read and apply philosophy to your life. But whatever is good about your life now -- don't get rid of it. As you understand more, you should only apply the knowledge in ways that improves your life.
But if you really try to understand everything about everything, you'llprobably feel more like you've wasted time.
You asked a question that's difficult to answer... either for us or yourself. Try to understand the purpose of your life. If you can do that, understanding of your actions will follow. Frankly, I think your actions are just effects.
The fact that you live and desire happiness gives you the right to feel a certain kind of peace... I'm not sure if you understand that. The various emotions you might feel can be attained in various ways, and you'll really have to figure out those ways yourself.
However, a general rule is to be honest with yourself and actively pursue your desires. While doing so you can try to understand your desires better and improve your efficiency at satisfying them, but don't spend too much time thinking. You need to act and your body needs to recognize that its being led to something good.