W
hat is the meaning of life? Or more specifically, what is the meaning of a human life? Though it seems to get obscured a lot in regular speech, "meaning" means "purpose"—to ask about the meaning of life is to ask about its purpose, what it is here to do. The meaning of life in general is fairly simple—to make more life. This is related to the fact that the purpose of being is to be (on analysis, this is the same as saying the purpose of being is to give glory to God). Things that are wish to continue to be, and the way that life is deeply involves generation.
This is the meaning that all life has in common. However, individual kinds of lives (like species), and individual lives themselves (particular beings) will have more specific purposes. As a rule, something's purpose is to be the best version possible of the kind of thing that it is, and this is clearest with living things—animals and plants desire to be healthy, to reproduce, to exercise their native powers. All animals desire to eat and rear young, but birds, for example, take on the specific purposes of flying and singing. The purpose of being a bird is being a good bird. All that is meant by purpose in this context is what the thing actually does given the sufficient means to do so; what is inherent in itself to do (i.e. this is not an argument for "intelligent design").
The more complex a being is, the more complex describing its purpose will be, and there are few, if any, things more complex than man. However, we can always go back to the principles we've established—a thing's purpose is to be a good version of what it is; which is to say, it expresses its native powers in a harmonious way.
What are the powers of man? They are many, and include athletic, competetive, rational, sexual/generative, social, creative, appreciative, spiritual/religious, virtuous, dutiful, and voluntary powers, among others. The scale of importance of these powers varies depending on whom you ask, but it is fair to say that the purpose of a human life is to give harmonious expression to as many of these powers as possible, giving each its due proportion as best as we can determine.
That, say, powers of excercising justice are more important than athletic powers is well-established, and all would say that a healthy, fit man who routinely commits injustice has made a grave mistake in the ordering of his life. Thus among the most important powers is that of ordering the other powers, as a composer orders the instruments in a symphony, knowing when each needs to be called upon, and which must take priority at each time.
Thus, the principle error that tends to be made in the ordering of one's life is that of proportion, of hypertrophy of certain powers at the expense of others. It does not help that the world in which we live is one that thrives on specialization of human beings, which means causing each to devote the lion's share of their time developing a small set of powers for the end of capital, and leaving others to atrophy.
Look at your life, and investigate which powers your routinely express, and which have difficulty seeing the light of day. And keep in mind that you are an animal, even if a complex one, and not an abstract "consciousness" incarnated in a temporary meatsuit. You are all of you, from your gametes to your corpus callosum, and you neglect any part of yourself at your own peril.