Not only do happy people endure pain better and take more health and safety precautions when threatened, but positive emotions undo negative emotions.
Martin SeligmanPositive emotion can be about the past, the present, or the future. The positive emotions about the future include optimism, hope, faith, and trust. Those about the present include joy, ecstasy, calm, zest, ebullience, pleasure, and (most importantly) flow; these emotions are what most people usually mean when they casually-but much too narrowly-talk about "happiness." The positive emotions about the past include satisfaction, contentment, fulfillment, pride, and serenity.
Martin SeligmanDoing a kindness produces the single most reliable momentary increase in well-being of any exercise we have tested.
Martin Seligman