I'm running around these walking websites and discovering that someone my age (almost 63) should be walking 4 mph to get a good workout. I get a great workout while walking (measured by HR and time) but travel "only" 3.3 mph. On the walking trails I pass some walkers, others pass me, so my impression is that 3.3 is a good pace, although I'm not going to win any olympic gold with it lol . . .