1. The Reach-Out; Improves Gratitude Write a letter or an e-mail to someone who has supported you or gone out of her way for you recently, and let her know that it mattered. Expressing gratitude can elicit positive emotions, which play a key role in boosting your mood, researchers say. (Check out other ways to boost your mood in minutes.) 2. The Joint Effort; Improves EnthusiasmLacking motivation to do the things you really want to do? Surround yourself with an energetic crowd—at a sporting event, an uplifting seminar, or even an aerobics class. Enthusiasm can be contagious and habit forming. 3. The Door Opener; Improves OptimismThink about a situation in which you lost out on something, whether the cause was bad luck or bad timing. Write it down, then identify a door that opened because of that closed one. This move helps you look on the bright side. 4. The Deeper Dig; Improves CuriosityRather than simply wondering about a topic of interest (oysters? art?), probe further. Read an article or go to an exhibit. Journal about your experience or recap it on Facebook. Learning—and sharing knowledge—foster curiosity. More from Prevention: How To Be A Bit More Optimistic