Does it? A lot of the people I know who've accomplished significant things did so not because they were happy, but because they tried harder than anyone else. They were not satisfied with the way things were and put a lot of effort into changing them. I myself didn't lose half my bodyweight because I was happy, quite the contrary, I hated --and still hate-- my body. That kind of motivation is incredibly helpful for overcoming the suffering required to accomplish big things.
Success will not make you happy, this my experience agrees with, but I'm equally sure that happiness will not make one successful.
Success will not make you happy, this my experience agrees with, but I'm equally sure that happiness will not make one successful.