Why don't I have the willpower to succeed?

I don't know where else to go but here. I am 27 years old and feel like I'm at a dead end job. I have dropped out of college several times, and can't seem to find the drive to do well. My fiance is losing hope with me and I am starting to fall apart. I know a lot of the problems have roots with depression but I thought I ped that phase of my life. Now I feel no joy in whatever I do unless it distracts me from the reality of things. I feel underpaid and that there is no hope in living well unless I finish school, something that I don't have faith in myself being able to accomplish. How can I find the willpower to break this spell. I have many talents but not the pion to flourish. I use to play music but I stopped enjoying that. I was working on my pilots license but I lost interest. Everything I try and like I end up losing interest. The only things I remain pionate about are traveling to foreign countries, and making my significant other happy. I wish I could find a career in traveling but I think I will have to complete school first. How can I find the self faith to be able to accomplish this?