Toiling in the Fields

I've been thinking about the city. Life in the city, you have to admit, is pretty far-removed from what we're biologically constructed to be doing. Typically, people who live in cities spend the majority of their day immobile (sitting in chairs, which is actually a stress on the body), sheltered from the elements, etc. Fantastic. We've been through all of that before.
But if we're biologically constructed to be doing something more like running around in forests trying our best to kill rabbits and find berries or whatever, what is the analogue for a city-dweller? Is there anything that we can do to sort of simulate for our bodies the state of being healthy and normal?
So I think about my city friends who seem well-adjusted to life in the city. One common trait that they seem to share is that they're all really active. Always attending some event, or going to some party/event/benefit. Picnics. Bike rides. Shows. It seems like one way to be normal in a city is just to try to keep as busy as possible. Social hunting and gathering. Because food's easy to find, but it's just not right to sit around all day. A leisurely life in a city is potentially quite detrimental.
Or you could just join a gym, I guess.

listening to: Sonny Rollins - Saxophone Colossus