The Good Gym matches people who jog for exercise with elderly and isolated people who could really use a visit. It's a brilliant idea.
Runners commit to one run each week, and figure out a time that works for both parties—usually after work or on weekends. You can see a BBC report on The Good Gym here.
The Good Gym won first prize at the 2008 Social Innovation Camp. The idea was refined and tested over following years and is now up and running, so to speak, in the Tower Hamlets neighborhood of London.
For the runners, it's a way of combining volunteering with exercise (because who has enough time?) and a way to stay motivated. For the people they visit—many of whom are elderly and socially isolated—it provides essential human contact and an assurance that someone cares.