Previous posts have talked about the cognitive benefits of hiking - walking in nature does a lot more for you than simply burn off calories. When you're walking at your own pace your working memory is better than when you're standing still and that working memory is important for reasoning and learning, for example. Being in daylight also boosts your mood and that makes it more likely that you'll have creative thoughts and get along with your fellow hikers. But there's environmental psych related research that can make your outdoor walks even better.
Recent research by Andrew Elliott and Henk Aarts ("Perception of the Color Red Enhances the Force and Velocity of Motor Output." Emotion, vol. 11) shows that you should probably hike with something red. Their work links seeing red and improved performance on simple strength-related motor activities. The benefits are found with tasks that require short bursts of activity - such as sprinting away from a bear. Red isn't a good choice if you'll be doing something requiring concentration - such as walking on a rope bridge over an abyss.
Smelling peppermint influences how you think about physical work you're doing, such as that hike. Research by Bryan Raudenbush at Wheeling Jesuit University in West Virginia shows that you should coat yourself in peppermint scented sunscreen, suck on peppermint candies, or somehow get a noseful of peppermint when you're hiking or doing other physical activities. If you do, your hike will seem less frustrating and you'll feel you're hiking better and with more vigor - hopefully those thoughts will keep you on the trail a little longer. As a bonus - if you're smelling peppermint your hike will seem easier than the same walk would if you weren't moving in a peppermint cloud.
So, when the weather is fine take a hike and put environmental psychology to work!