Whether you're collecting trash along the ocean's shore, helping out at a retirement home, or walking shelter dogs, volunteering is undoubtedly a great green activity that lets you get out of your box and do something for someone other than yourself. Now, more than a do-good pursuit, you might also be able to make your contribution a multi-tasking activity, especially when it comes to hanging out with rescue pups. Research from the University of Missouri at Columbia showed that volunteers who walked shelter dogs for an hour a week also lost weight—about 12 pounds a year. Up your dog walking activity to 20 minutes a day for five days a week and the average weight loss goes up to 14 pounds a year! Volunteering at a shelter is, sure, great for the dogs, but it's great for your mind and body too. Some studies have shown that about 70% of people who commit to those weekly walks keep it up long term (and often stay longer than an hour)—which is a much higher rate of return than any average exercise program. Not sure that dog walking is your cup of tea? Determine your volunteer personality then make sure to incorporate an active angle, like walking along a local trail picking up trash or preparing food at a neighborhood food bank. The great news is, even if you don't lose weight, you know you've done your part to help the environment or another person today.