I once listened to Amby Burfoot, legendary runner, speak at a local pasta party before a race.  One thing he mentioned was that he had a friend who was still running in his 80’s.  He asked him when he plans to stop and his reply was “You’re never too old to start running and always too young to stop”.

This article backs up why it’s never too late to start running.  http://www.runnersworld.com/health/why-its-never-too-late-to-start-running

Keep running and if you don’t run, start!