When I can, I go jogging in Central Park for 4 - 5 miles 2 or three times a week.
When I'm in shape I do the whole round which is exactly 6 miles, but then I have to rest for a couple of days before I do it again.
It's a great exercise for me, but unfortunately every now and then I stop doing it because I don't have much free time, and when I start again after a couple of months I have to take it easy and go for just 3 miles run until I get used to it again.
But I would definitely recommend it to anybody.
I never read a book though, I just do it !