Let me start by saying your movement is meaningful because you are moving for YOU. On top of that, there are SO MANY ways that you can move around and help others. If you are looking for ways to increase your activity and increase your contribution, here's some ideas!
Walk your dog a little longer and make their day! Alternately, or if you don't have a dog, make the day of other dogs by volunteering at a local adoption shelter or walk the dog of your elderly neighbor. Dogs are sweet, wonderful souls and they really appreciate the time you can give them!
Volunteer at a camp (sleep away or day camp). A day of playing with young friends goes by so fast that you don't realize you're tripling your steps until you look at your watch!
Organizations like Meals on Wheels and other Senior Service Agencies give you the opportunity to help our elders while moving around. Sometimes just stopping by a caregiving facility and asking "who needs a visitor?" can result in a walk outside with a brand new friend!
Babysit. Take your friends' kids to the park, your nephew to the batting cages, or play in the sprinkler with your neighbor's visiting grandchildren.
Take to the streets with a polling agency or petition that is close to your heart.
Fill out the stage as an extra or help build a set at your local community theatre. You will meet some amazing, selfless creators and have a LOT of fun!
Go shopping for someone who can't easily make grocery runs. Churches and Social Service Agencies always have a list of folks who need your help. Most will reimburse you for the grocery run and provide a very specific list so there's no questions.
Got other ideas? Post them online and tag me!