Karma
A primarily Hindu belief that ties in with reincarnation- if you are good and build up good karma in this life, then next time you might be reincarnated as a Brahmin, or a Kshatriya. (In Hinduism, the only caste that is able to become enlightened thereby escaping the endless cycle of rebirths are the top caste, the Brahmins).
If I'm really good, maybe I'll get enlightened.. yay!