The line that jumps out at me the most from your post is, "they seem to be having fun, I'm not." If that's the crux, I might venture a guess that if you made a list of 10 things you would like to do at some point in your life every day, life might get a little better. Every day add 10 things to a list that you want to do before you die. Some of those things are bound to come true, especially if you write them down. Trust me.