A recent article at theAtlantic.com reviews some of the research on exercise as a treatment for ADHD.  The studies mentioned were done with children, as most ADHD research is, but the evidence is strong that exercise is also an effective treatment for adult ADHD.  I encourage you to read up on this topic, as well as watch John Ratey's 2012 TED talk on the subject of how exercise helps your brain.  If you weren't inspired to get moving before, you will be now!