I think parents are waaaay too soft now.If families go on a hike soon as little Jimmy whines they turn back.It's part of modern parenting,kids call the shots far too much.In my day you just got on with it.
We're far tougher with ours now they're 7,7 and 6. We've started hiking the moors again.We have plenty of rests,don't make them carry anything and always end up by a stream for a long picnic but they finish the hike wether they like it or not. It's not a marathon,just a couple of miles which we're gradually increasing and they love it.It's the same with bike rides,sorry but we're not doing turning back after carting 5 X bikes out, I know many people would think we're mean.
We do this in London/cities too ie get from a-b whatever. Stop for breaks and keep an easy pace but basically get to where we set out for,gradually increasing the distance.
I think far too many families do this soft expensive play/theme park shite at the weekends so kids just aren't used to exercise as a regular cheap fun activity instead.
Maybe things will change with the austerity measures.