I think they are probably less motived than we were as kids and my opinion is educators(school) and TV Programmes succeeded where they didnt.
I insisted my sons play a sport every Saturday morning ( and it was hell some cold mornings standing on the soccer line freezing my bum off) but worth it in the long run ,they got to like it and helped create a healthy habit.
No TV's in bedrooms and no Playstation during the week,that was the deal( before we bought it) and they agreed do it, after they were older I was more lenient since they had already learned to prioritise ( mostly) lol. Sometimes its the boundaries we set kids that either help them be lazy or not . Motivation can be grown ,just my opinion