Resistance training is a very important thing for everyone to do—whether they're a man or woman, young or old. We lose muscle as we age, and this is a really underappreciated fact. It's even detectable when someone is in their thirties. This accelerates over the years, and by the time someone is 80-years-old, they may have lost half the muscle mass they had when they were young if they don't do something about it—and of course, most people aren't doing anything about it.