If I may: bottom line is that it's not an either or. Because we start to lose both muscle and lung capacity when we pass peak reproductive age (about mid-twenties), we need to do BOTH. Finding how to do that, how best to give our bodies the necessary aerobic workout AND push our muscles is a life long journey. Each decade gives us a new chance to figure out what works, particularly if you, like me, have accumulated injuries. We need to find workarounds, but we also must find joy in body work. Or we will trade that time for butt time with the remote.