You do realize that being happy can come from accomplishments. Being happy doesn't mean you are some bubbly fellow walking down the street singing in the rain. I find all my happiness comes from my accomplishments. Making grade in the military, taking care of my family, watching my kids grow up, moving to another career after the military, buying a house, etc...
If you can't find happiness in your accomplishments, by all means go join the peace corps and try to find something useful to do.
Everything I do, I do because it's what will make me and my family happy. Why in the world would you do something that wouldn't make you happy? That seems fairly counterproductive to me. As if it won't make you happy, you won't be motivated to give it your full attention.