When I think about what makes me happy in life, I think about the people and the things I'm passionate about. They can be simplified into two senses: a sense of belonging and a sense of purpose.
A sense of belonging is vital because it ties in to our basic human need of connection. Inherently, we are social beings; we want to create strong relationships and find people who accept us and encourage us to be the best versions of ourselves. Whether you are an introvert or an extrovert, you get joy from laughing with friends and experiencing a special bond with another person.
This sense also explains why we become friends with certain types of people. Some people might point out a kid who is involved in a lot of dangerous behavior and think he or she just "hangs out with the wrong crowd," but they don't always stop and think about why a person would do so. The answer lies in his or her sense of belonging. If you feel accepted by a group of people and you haven't felt that way with anyone else, you're naturally going to want to be with them.
The other important sense is a sense of purpose. Most people have heard questions like, "Why are we here?" or "What is the meaning of life?" I think we can define those questions by finding what makes us feel like we have a purpose. Whatever adds meaning to our lives and makes us feel important and needed falls under this category.
One of my relatives was out of work for a while and was struggling to find a job. This caused her to feel like employers thought she was worthless and incapable of contributing anything of value. Although both senses relate to self-worth, I think a sense of purpose is more related to self-worth derived from self-sufficiency.
The two most important senses encompass everything that gives your life meaning and value. Without these, life would be a seemingly endless road to nowhere.