I just commented on this in another thread here the other day.
I found this forum because my finances went into a tailspin and my business went down the tubes during a time when I was really, really happy. I came here searching for answers.
I could probably make a huge list of times when I was really happy and outside circumstances went bad, and times when I wasn't doing well emotionally and outside circumstances got a lot better.
Saying 'just be happy and you'll attract everything you desire' may be simple, but it doesn't work for everyone.