Both my husband and I were much more active pre-kids than we are and are able to be now. We used to run regularly, my husband to a high level (sub-2h40m marathon times) spend whole days or weekends away riding mountain bike trails, doing triathlons, and taking active holidays - skiing etc. All of which are impossible to replicate with toddlers around. And the lack of sleep in the early months (years in our case!) is also a complicating factor.
I know that not all MN users have kids so am curious to know how many posters on this thread are parents. Childcare and time (both tp train, and rest / recover) are the main issues when it comes to fitting in exercise and sport when you have kids in my view.
My husband works FT and I'm PT. We only have 1 child but with not many babysitters available, finding time to exercise is hard. And we enjoy spending time with our son too so don't want to spend masses of our non-work time away from him.
My husband has changed sports as doing running and triathlons now doesn't interest him as he'd never match his old PBs as he can't do the training needed. He now does tennis and gym sessions with a weekly run, but time remains a challenge.
Maybe when our kids are older, more independent, going to bed at a more regular time and waking up at a more reasonable hour, are at school we'll be able to do more, and hopefully with them as they get even older.
But I'm being realistic for now. Home workouts for me, weekend walks and hikes for us all, the odd run together with DS in the running buggy etc.
If only our local swimming pool had decent lanes at the weekend. DH and I could do a swim session each, taking turns to splash about in the other bit of the pool with DS. But they don't. More integrated thinking from sport and leisure providers would really help parents to exercise and stay healthy. Leisure centre creches should be just the start....