At a high enough body weight, even walking is resistance training. Or even at a lower body weight, if what it's being compared to is total bed rest or otherwise being very sedentary. I feel better if I get in some minimum of walking through the day, even on top of working out with weights. Never got much out of high volume aerobics though, I don't seem to get a training effect, no noticeable improvement from running. The only thing that seems to improve that for me is losing weight.