It has become increasingly common recently to construe human natureas setting some pretty stringent limits to moral endeavour. Many consequentialists, in particular, take considerations concerning human nature to defeat certain demanding norms that would otherwise follow from their theory. One argument is that certain commitments ground psychological incapacitiesthat prevent us from doing what would maximize the good. Another is that we would be likely to suffer some kind of psychological demoralization if we tried to become significantly more selfless. I argue that influential versions of both of these arguments underestimate our deliberative resources, and also fail to examine the kind of moral sources that may be able to sustain rigorous moral endeavour. Pessimism about our capacities for such endeavour results from the neglect of these factors, rather than from uncovering any significant limitations in human nature.