You don't have to know what your going to do with your life, just do it. You can't fail in life if you do what you love, and you enjoy living. :o
Life doesn't have to be all about preparing for the future. Become a milkman in a small Jewish village in Russia, who sings every 20 minutes about life. It worked for me! :D
But seriously, do what you desire to do, (So long as it doesn't hurt anyone or breaks too many laws...) find a calling, be happy. Life isn't all about money and success. Society often blows it up to seem that way. Remember, when you die, you can't take any material thing with you. :o