The great outdoors can put a spring in your step: Research published in the June 2010 issue of the Journal of Environmental Psychology found that people who walked outside felt more energetic afterwards than those who walked indoors. Exposure to nature, fresh air, sunlight and the feeling of openness may contribute to that sense of wellbeing, the scientists wrote. Hiking and bird-watching also are linked with less stress, Yale scientist Stephen Kellert wrote in his book The Biophilia Hypothesis. While there's no guarantee that being an outdoor aficionado will make you eco-friendly, it may inspire you to act environmentally responsibly, British researchers reported in 2009. Try walking, biking, or even doing a crossword puzzle outside to get a nature fix, Frantz says.