Yes, happiness is a CHOICE!
I was actually reasonably happy while I was living in my car... because I had a truly clean slate to rebuild from. No complications. It was remarkably freeing.
If there's one thing I have learned-- and I never hesitate to pass this along(!)-- it is that we should always do our BEST, but we also need to be open to the possibility that sometimes "our best" isn't good enough to accomplish some elusive goal we may have set for ourselves. And we need to be OK with that.
Meanwhile, little things in every single day we live have the potential to make us feel happy. We just need to be open to it.