The meaning of life, quite simply, seems to be to love and be loved. This sounds like a small portion of our lives, I am sure. When you really step back and look at things, though, you'll see that almost every action done to a person is done to get some sort of reaction. For example: A boy gives a bouquet of flowers to his girlfriend, no doubt he is expecting some sort of praise or reward back, be as it may. A person talks to another person, most likely he is expecting to be responded to. A child cleans up his room without being asked, chances are he is seeking favor in his mother's eyes. All of these are actions that, while truly requiring no reaction, are still rather expectant of one. Love does not have to be in the form of compassion; it can be any act of kindness, goodwill, or even simply tact. Thus whenever you do something seeking one of these, you are -- whether inadvertantly or not -- seeking to fulfill the meaning of life.
Now you may be thinking, Yes, it is true that man seeks reaction upon action, but that hardly makes it the meaning of life. Yet it does. When action is not met with suitable reaction, over a period of time man declines in perception of worth and purpose. Even in the strongest of men, decline in these areas eventually lead to suicide. Sad, yes, but oh so very true. If man does not love and is not loved, or in parallel, does not react and is not reacted to, all of mankind will eventually commit suicide, and there will be no life left. If the very thing that keeps us alive is not the meaning of life, I truly wonder what could be. By being loved you are preventing yourself from extinquishing. By loving others you are preventing others in your own race of mankind from being extinguished. Thus simple reaction upon action saves mankind. Thus loving and being loved is the meaning of life.