In VA beach around St. Patty's day is the Shamrock Marathon and 1/2 marathon. They let you pick a charity and run for it. Best part though is that they are sponsored by Yeungling (the best beer in America) Eventually I'd like to try to run it just to get a green shirt that says "Yeungling" and then get to drink beer at the finish line!
Near Philadelphia in May there is a 6K run (the average distance African women walk each day to get water) to raise money for clean drinking water in Africa ( it's put on by my dear friend and fellow ballerina, Kristin Scott's non-profit COMEUNITY)
Locally, there is the Greater DC Cares Servathon on April 16th, where we'll be out beautifying local parks and schools for the day.
Street Sense. It's a newspaper sold and sometimes written by the homeless. Its a opportunity for the homeless to start earning money to help them put their lives together. In addition it's a good read. Now that it's getting warmer, it's easier to stop for a chat and buy a paper from one of the friendly Street Sense vendors.
Look out for AVON, JDIFL and Komen 3 Day for the cure Breast Cancer Walks. Shout out to my Aunt Peggy for being a survivor!
American Heart Association has taken an initiative to get everyone walking for that.
These are just the ones I know about. So, even if you don't have a green thumb, you can grow something--you can stretch yourself and help the world grow a little this spring by getting involved in one of these activities that are sure to be fun or good exercise or both.