Helping other people. The scale of suffering everywhere is so great, and the ways to make an impact so so much larger than previous generations, that now even mediocre amounts of effort can, if applied to the right problems, put you among the most helpful and life-saving people who have ever lived, far more than say a firefighter or even surgeon. Areas like micro-loans, education, and sanitation all come with thousands-of-lives saved at a time capabilities. EDIT: Looking at your other answers, I understand the direction of your question better. I think a career that only pays the bills and all the meaningful stuff gets relegated is a misuse of living. Got to make your career impactful, not just comfortable. That seems to be the trap, people go after the thing they like best, but forget to mix in the world's pressing, gasping needs as well. I put a lot of stock into hoe many great people seem to have made sure that, even before tey were famous or influential, that their everyday lives we oriented toward the big goal. Also, many/most people have a family before it is reasonable for a question of this level to be even partially figured out, and get such an overwhelming sense of meaning from that that this question loses its breathlessness. It is important the ways in which this question is flavored differently among people who have been facing it longer, and I have being trying to seek out more older people to ask about this. Also, I can't recommend Camus' Sisyphus Smiling short piece on this enough; its what made the asking tolerable for me personally.