All life, at least all intelligent life, is wrapped in a conflict between two continuua.
The first continuum concerns the choices we make. Choices come in three flavors: A choice between that which we want to do and that which we do not, a choice between things we want to do, and a choice between things we do not want to do. As we get older, we will naturally experience more of category three and less of category one.
The strange thing about these choices is: they do not always correspond to the benefits they provide. A choice between many things we want decreases our overall happiness with the outcome regardless of what that outcome is. A choice between two things we don't want is a slavery, and if the choice was presented because of a choice we made earlier, then it is a self-induced slavery. We had better hope that the time we spend resolving the effects of those choices is worth the benefit of getting ourselves in that situation, because otherwise we've made a stupid decision. There are worse things in life, and stupid decisions have resulted in some of the most spectacularly positive discoveries in modern history. But mostly they just suck and we feel stupid for making them. Also, being stuck in a decision between two things we don't like tends to beget other decisions between two things we don't like. That's called stress. The wages of stress is death.
The other continuum has to do with vitality. The tension caused by hope, the desire to strive, to prepare for some future benefit not guaranteed, but anticipated, is the source of personal vitality. If we aim our goals low, we will find we aim yet lower every day. For some the decision to get out of bed in the morning weighs as heavily as matters of Solomon. For those aiming for the stars, they may not reach them but they certainly go further.
There is no limit to how much good we can do. A surgeon working tirelessly may save two or three lives a week for fifty years, netting him 5000 lives saved. That same surgeon may develop a technique that saves many more lives, or learn something important about disease and injury that saves even more lives. But we have to make choices that get us to a position of helping people rather than being helped by people, and we have to have enough personal vitality to make the maxium difference.