Sport is simply recreation for some. Some kids might be naturally gifted but they don't place it on a pedestal. I was never going to be a star cricketer but even if I was good at it I was only ever in it to play the game for fun and to socialise.
A mate of mine could have easily played Sydney first grade, possibly state, but his heart was never in it.
Give your kids encouragement, and if they do develop that want to be the best in their sport, that's when the push and the home truths should some. If it's just a a bit of fun to them there's no need to drill win at all costs attitudes into them. Just because they have a lackadaisical attitude to sport it doesn't mean it will translate into every other facet of their lives.