When I was in school the President (I believe it was Coolidge) challenged all us kids to get in shape.  Well the President's Challenge is not just for kids anymore.  Check out, and sign up for the free competition at presidentschallenge,org. 
The site has programs for kids, teens, adults, seniors, and a separate program for educators (apparently teachers require a

different set of exercises).  To participate you must exercise 30 minutes a day, five days a week.  There's about 100 activities ranging from gardening to bowling.
Try the championship program which awards points for activities based on how strenuous they are.  For example, a half-hour of vacuuming earns 73 points, while a 30 minute run