I consider two miles to be not unreasonable for a walk, assuming I'm not burdened with packages (or uncomfortable clothes/shoes) or in a hurry. I think I'd be fine with walking double that, but time constraints kick in so I don't. (Heck, while I walk the mile each way to my synagogue on Shabbat, I'll drive over for meetings during the week, just because it's a ~6-minute drive vs a 20-minute walk each way.)
walking distances