When my first post-doc wasn't working out, I went and spoke to the head of post-doc affairs at that institute, a famous woman scientist. She was very supportive and sympathetic about my decision to leave and admitted that my situation was not the first she had seen come out of the lab that I was leaving. She gave me some advice on how to find my next post-doc and her parting advice to me included the line about happiness, but I know how miserable I was in the months that followed.
Two years later, at a huge international meeting I bump into her. I introduced myself and thanked her for her advice and support way back then. She seemed to recollect. Then I told her how well I am doing now, about my work and the awards I have gotten. That her advice was well taken and I am indeed a very happy person today. It felt so great to share my accomplishments with her and I am riding on that high ever since.