Richmond Sailfish

Our son did Richmond Sails swim team at the plunge for years (2 x/week).  It is structured but kind and doesn't push the competitive side of swimming.  Their head coach, John, is a junior high school teacher and really gets kids, especially boys.  Our program was: starting at age 8, you must get two days a week of exercise no matter what and until you find something you love, swimming is it.  

Now, at 14, our son bikes and on his own does a 30 min cardio in his room most nights.  We bought him a boxing glove and pad set.  He's got the pads taped to his wall and includes a rigorous set of "boxing" in his workout.  You might consider buying some interesting workout "tools" and having silly fun time with them.  We have a wheel that you stretch to get an ab workout and it has caused much hilarity at our house . . .