High quality social relationships help us live longer, happier, and healthier lives--facts that hold true, as far as anyone knows, regardless of geography or culture. Although links between relationships and health have been observed for decades (if not millennia), the reasons for those links remain speculative. We know that our friends and loved ones make us more resilient in the face of stress, but we don't really know why. For this talk, I'll first describe my work on one of these potential reasons: social regulation of the brain's response to perceived threat. Next, I'll offer a perspective--derived initially from our social regulation results--that integrates the study of social relationships with principles of behavioral ecology and cognitive psychology to propose that social relationships are construed by the brain as bioenergetic resources available to the self. Because of this, proximity to social resources economizes both current and predicted cognitive and bodily effort, a process that relieves subjective stress, improves health, and prolongs life.