I think if you are walking at a decent pace that you can count it. What I do sometimes if I am doing something that is exercise but not very vigorous exercise is I'll prorate it. If I am walking from door to door with my son selling popcorn for four hours, I might count it as one hour of walking since we stop at each house. So I might suggest you count part of it if you are just strolling at a slow pace and all of it if you are walking at a decent pace.
Barbara - Started South Beach 5/22/4
HW/SW/CW/GW - Jan start 169 goal of 2