It makes sense to me, if you look at this article. That activities that entertain us, fulfill us, connect us, uplift us... they make us happy. While activities that we feel we "have to do" make us less than happy. Activities that stress us out, decrease our level of happiness.
So it seems the road to happiness is an easy one then right? Choose to do things that lead you to more fulfillment, more connection, being more uplifted. That lead to less stress. Make a joy list. Do things on your joy list. Don't do things that aren't on your joy list. Or at least try to minimize them anyway.
You might say that we all have to do things we don't want to. But do we really? If you practice reframing, you might get really, really good at looking at the world from the perspective that everything you do is something that brings you joy and towards happiness.
You might not be manageable to be around but hey, you'd be happy. :)
Have fun reading and please, go out and do something today that brings you a little happiness please.