[rubidium]

Ah yes, your city environment will make it more difficult. That said, if he's old enough to bike (and the city you live in has some bike safe areas) then that's a great hobby to push. Taking 30 minute walks around the neighborhood is another. Regularly going outdoors (taking a walk together, visiting parks, any local state parks) as a family helps. But yea, if you're not doing it it's not going to transfer well to your kids.

Regarding setting rules: Kids are very bright when it comes to getting their way. If there's any loopholes they'll exploit them. If they detect weakness in resolve then they'll push and push using negotiation, guilt, deception, etc... The question they're trying to figure out is, is my parent in charge or can I be? The hardest but best thing you can do as a parent to instill disciple is to be clear, consistent, and follow-through. It's really hard. I'm in the midst of it too!