well judgment day depends on belief as well
technically, you shouldn't need an incentive to lead a good life...that means you're not a moral person for morality's sake, but for your own sake.
Read some Immanuel Kant. Although his philosophy of ethics is bogus, he does get a few things right in there. For example: if you're leading a good life with the aim of having a great afterlife (paradise, or whatever you believe), then you're actually leading a self-centered life.
So. Lead a good life for it's own sake. Worry about life after death on your deathbed, or not at all.