I agree. For several years after I moved to city rarely a day went by when I didn't walk 5+ miles. I enjoyed it, with all the hills it kept me in pretty good shape, it allowed me to get much more familiar with neighborhoods. But lately some L hip arthritis seems to have put a cap on the amount I can do without pain. Some days, 6-7 miles is fine, especially if it has few down slopes. Other days it just isn't going much above 3 miles with comfort. So I went ahead and ordered my Concept2. Rowing can be used any way that running/ walking can be - fast intervals, long slow distance, or like a race, as fast as one can keep it up for say 5000 meters. Also, I've noticed that rowing even feels restorative on my hip. Yesterday I had walked about 3.5 miles in late morning, and I wanted to do ~3 more, but I was going slower and slower. I was supposed to go out to my woman friend's in the afternoon. She called an told me if I didn't want to miss lunch I had better get to the gym to finish up faster. So I finished off on the rower in the gym ( my chain has one near her), got all the calorie burn I wanted completed for the day, and still made lunch.
I've come to think that the the guys in the 70s weren't wrong. Go daily, go a considerable amount in as many doses as you care to, and don't always be pushing. It is easier to walk along at a moderate pace, outdoors on a pretty day, with attractive natural and human visuals, but every day isn't pretty and with my required daily calorie burn taken care of before I leave home, just walking to Trader Joe, or perhaps going down to the park or walking around a nearby college campus will be something on the top.
Ha