been doing the same job for 24 years. i do a lot of walking,,,on concrete. it ain't exercise by no means. that stuff is poison at its best.
i attached one of those gizmos that measure how far you walk. one ten hour day = 9+ miles of concrete. i agree that walking is good exercise ,,,,if you are walking in grass , where you must pick up your feet. want more ,,,walk in some fescue about 6 - 8 inches tall,,,add some incline and you muscles will ache,,,for a day or two.
i don't claim to be in top condition ,,,toward the end of spring season i feel a lot better than i did early on.