I like to think of happiness or positivity as being like a muscle. Most people don't realize it needs to be worked out. If you really make it strong, you can stay positive no matter what happens. Practice is one way to make it strong, discovering certain truths is another.

Questioning self-limiting beliefs is also something you can try in order to build perspective which gives you more freedom to be happy. "If I don't get into this school, I am not going to get a good job", thoughts like this are very limiting. I want to write about this soon.