Fit and happy are not mutually exclusive, and I can't imagine living in a world where being unhealthy, with bad joints and body odour, stigma,  a lack of potential mates, and perpetual anger equates to "happiness". Fit means you are attractive, capable, independent, and lack the constant inhibition of being rejected and demoralized. Seems like a pretty happy way to be, if you ask me. Besides, happy people don't feel the need to convince everyone else how happy they are as though they have something to prove.....