Find out about past lives and reincarnation.

You live a series of lives in different physical bodies. You come back to live a life over and over again in order to learn. There are lessons that are repeated to you so that you can grow from the experience and make progress. Progress to what? Reincarnation is the process you go through in your path to enlightenment!
		So who gets to pick the life you lead? The answer is, you do. Wait, before you jump up and down in excitement planning your life as a rock 'n' roll god, consider that when you decide on the type of life you will be assigned you are in a state devoid of your ego. You make your descision based on what you still need to learn with disregard to 'earthly' pleasures.
This process is governed by karma. This is the force of cause and effect that binds us to the lessons that we need to learn. As we act there is always a reaction. In terms of energy this reaction needs to be balanced and this balancing act is karma.