Why God? Why not yourself?

My question is why do most trace of success, triumph, pain, and suffering back to "God"? I am not Christian, Catholic, Jewish, I have no name for my religion. My religion is living a good life. The fact that I live a good life is enough for me, I believe I overcame obstacles in my life by my own doing, by facing them and realizing what needed to be done. Do not get me wrong, if their is a God and he shows me that he helped me out i'll be grateful without a doubt. People say i just have to believe that's the only way to have a good afterlife. I believe knowing im doing my true honest best everything will not be good but will make odds of happiness a lot greater. The only punishment i hear for not believing in god is reliving basically a "worse" life. But i believe we make life what it is, and i do not believe life is so bad. I believe when someone pes that their not watching every little thing I do, but their occupied somewhere and their happy.(the next stage of life). They may be gone in this life but are learning the next life to teach me when i reach it. Is it really that bad to believe I overcame obstacles, troubles, and became self motivated all by myself?