If you're one of those people who is constantly searching for the meaning of life, you're already screwed. Men and women have spent their entire lives dedicated to that question and in the end they all just died anyway. When we think of Plato or Aristotle, all most of us can think of is some image of a naked guy scratching his chin in what looks to be an uncomfortable position. Now seriously, do you really think anyone who spent their days interpreting the world's great mysteries would be that ripped? No offense to Aristotle, he was cool enough I guess but his life turned out to be almost worthless as over half his theories were completely incorrect. But the important thing is that he did what he loved and he survived.
The meaning of life my friends, is to do what you enjoy so long as it doesn't hurt others and too survive. Everyone's life is different and some people get more crap to go through than others. You can't convince yourself you're having fun if you're not, nor can someone else just come along and make you happy for long. Aristotle showed us the meaning of life and that is his greatest achievement. Now I could get into energy fields, past lives, the theories of different religions but basically what it all comes down to is finding something that you love and are good at, discovering what you need to be happy and obtaining it and being nice to people. That is the purpose to every life. You can have your Karma or your Ph.D. in this or that, or be a bricklayer and if that's what you do and you're happy, you ROCK! If you're not happy anymore, find something else to make you happy.
The keys to the meaning of life are these three things:
1) Survive. (Work, obtain shelter and food, find love if you need it as most people do.)
2) Be kind to others. (Every culture, metaphysical experiment and religion says that if you're bad you're either just dead or you're in for a nasty time after you die. If you're a sweetheart or just not a jerk things work out better for you.)
3) Discover what you need to be happy and get it, if it changes, go after whatever new thing takes its place. (It may sound hard but if you can't figure it out consult a therapist, psychologist, spiritual leader, etc... whatever, that's what you and the government pay them for. They know their stuff and if they don't, find someone else who does.)
That's it. Those three elements are the meaning of life. Of course you can add whatever you want on to it to accommodate yourself. But go to any university, theological seminary, cult (not always a good idea) or any institution you choose, you can even just sit around and watch TV and you will discover that I am absolutely correct. Life can be as simple or complex as you want but these three keys are essential to unlocking any door you come across in your search or a meaningful existence.