Luckily, Mike had a great idea. We've started taking the boys to his school at night after dinner. Nicklas works on his homework and Seeger watches movies on the projection screen. Then Mike and I do labs around the second floor, stopping to check in on them every lap. The boys enjoy it and we like spending the time with each other while working up a sweat.
(Of course Seeger is watching a Thomas the Tank Engine DVD!)