<p>A number of philosophers have argued that pleasure and pain are asymmetrical with respect to their contributions to well-being: the degree to which an episode of pain is bad for one is greater than the degree to which an equal quantity of pleasure is good for one. In this paper I defend an explanation of the asymmetry. I argue that pains, and some pleasures, are instrumentally bad for us in the short term. Notably, this is because pains and some pleasures are partially self-defeating: they motivate us to pursue certain ends while at the same time distracting us from pursuing those ends. This may seem paradoxical, but I argue that being self-defeating is a nearly unavoidable feature of any system whose function is to alert us to problems and direct us to find solutions.</p>