(Another old thread I'm adding my 2cents too!!)
A requirement of my current training plan is 6 x 30min walks (ideally 1 each day of the week - 1 day off).
They aren't meant to be leisurely 'sunday strolls', a strong 30min walk should slightly increase your body temperature & definately increase your heart rate.
If neither of these is happening when you are on your walk - you may need to ask yourself, 'are you going fast enough?' This is usually one of the most common problems people find when they question the effectiveness of a daily walk.
Hope this helps -xx-
J-H
Reception - Donna Aston Studios