Many people do enjoy their lives. My sister chose to become a nun, against the advice of many loving relations and friends, and seems to have found a life she enjoys fully. Significantly, I think, she has the intelligence and the education needed to be able to analyse external pressures from her peers, from society at large and from cultural expectations and to reject those which threaten her quality of life.
Unfortunately most people live in a world that constantly urges them to do things that they either don't want or are not able to do. It is quite difficult to take time, stand back and think objectively about one's life.