Not motivated to go walking, even though you know you should? Joining a walking group can help. It builds relationships and boosts mood more than going solo, according to studies of more than 2,000 people. A review of the research, which was published in the British Journal of Sports Medicine, found that three-quarters of people who tried walking groups stuck with them. To find groups near you, check out mapmywalk.com and walkers.meetup.com.