well you get pushy parents in all areas of life, but you can only lead a horse to water and not make it drink.
ie my eldest son, from a young age, ie when he could first walk he had no interset in climbinb, running, kicking a ball etc, still at 11 he is really not sporty, he does pe at school and as a family we go on bike rides, walks etc, but he wouldnt always come if we didnt say he had to and when we get to a play area etc he tends not to want to climb on equipment etc unlike my younger three boys.
ds2 however, crawled at 5mth, walked at 9mths and climbed as soon as he could crawl, is a very physical child and on the go NON STOP, totally obsessed with football, despite having an elder brother and a father that dont really like it, he would play it all day, eat, sleep, breath football is a statement totally true of him. he is now 8 and very sporty, loves PE, bike riding, scootering, korfball, football etc you cant keep him still!
ds3 again very physical, not so keen on football but rode a bike wiht no stablisers just after his 4th bday and regularly goes on long bike rides, he can infact ride better than his elder brothers, just natural co-ordination and balance.
ds4 seems to be a mix of ds2 and ds3 likes scootering, loves running and playing football etc.
we dont push them to do anything, tho we do strongly encourage ds1 to do more exercise/sport, purely because he does so little and also has a tendency to overeat, he just loves food and always has done and if he didnt exercise he would no doubt have an issue with weight which we dont want.
i think on the whole kids can do more exercise than we give them credit for,t hey are designed to be physical and as a general rule will stop when they need to.
can you push them to do more? undoubtably yes, can you make them do so much that they would hurt themselves? maybe tho in very young children i would think it hard as they do just stop what they are doing.
and if you push a child and they come to love that activity and excel in it thats not always a bad thing? i am sure many top sports players have had moments when they havent wanted to train etc and they were encouraged/ coerced to do so and reaped the benefits in the long run.
like many things its a very fine line, but i do maintain that most kids dont get enough exercise and worrying over them doing too much is prob not a huge issue.