Just to clarify I'm not planning on doing this yet as I think he's too young, it's just a musing for the future.
I'm a single parent, DS is 8 and a half. I'd like to join a gym in the future and go to classes as I just can't get motivated to lose weight at home! He does go to his dad's house but only around 3 nights a month.
What age did you all start leaving your children for an hour to do stuff like this?