Since I'm a grad student and I have zero extra time for exercise during my day, I've chosen to walk to my classes every day so that I get at least a little "accidental" exercise. It's 2.1 miles to my classes on campus, and I time myself taking about 45 minutes on my lazy/tired mornings. Other mornings I try to speed walk the whole way... when I timed myself the other day, I walked as fast as I possibly could the entire way, and by the time I got there I was nice and sweaty for my 2 hour class (lovely, eh?). Unfortunately, it apparently still took me about 35 minutes... which works out to be only 3.4 mph! I estimate this to be right since on my treadmill I can't really walk faster than 3.5 mph w/o needing to hold on for dear life.
Why do I walk so slow? I keep reading online that I need to walk 3.5-4.0 in order to get a good work out, but I literally cannot walk any faster than about 3.4. It makes me feel pathetic. Is it just that I don't have the muscle mass, or is it because I just have a short stride? (I'm only 5'2") Does anyone else have this problem?