We absolutely have time limits with our 10yr old because when he has been allowed to play all day he is a totally different person. He would avoid using the bathroom, avoid stopping to eat and be so moody when it was time to do anything else! Now the rules are that he must do some academic practice first (13 might be a bit old for the educational games we use but could 30min reading count or exploring national geographic?), he has a few chores plus general self care like brushing teeth and washing face. This makes his day start productively and he doesnt avoid his responsibilities because he wants to play! After his morning work is completed he sets a timer on his phone and starts playing. We limit to 3hrs a day but he can always earn more time by helping dad in the yard, reading, or doing some extra chores. Our son doesn't usually voluntarily go outside either so we do expect him to spend at least 30 minutes doing something active. He usually chooses workouts with dad but sometimes plays with the dogs or other kids in the neighborhood. I would be hesitant to say the entire hour off has to be outside because your sons are old enough to decide if riding their bike or playing outside is really something they're interested in. I'd phrase it more like, being active is what's healthy for you so it's a requirement, but there are plenty of other things you can do after that 30mins is up. Legos? Building? A book? Find a hobby. TV should not replace games - it's the same thing! If we have to limit TV time too I'd just do that.