What I'm going to say it's pretty close to what's on /r/im14andthisisdeep, but for some people (including me) finding meaning in their lives is a very good reason for happiness.
Meaning can give you a sense of wellbeing but it's considered to be separate from "happiness". [1]
E.g., parents rate relatively low on happiness yet are still "happy" that they have children. They have a sense of wellbeing from something meaningful.
