http://time.com/4803697/bodybuilding-strength-training/?utm_source=pocket&utm_medium=email&utm_campaign=pockethitsFor strength and longevity, resistance training may be the best kind of exercise. He says lifting “almost to failure”—or until your muscles are near the point of giving out—is the real key, regardless of how much weight you’re using. “This is a huge boon to adherence, because many older adults or those with injuries or joint issues may not be able to lift heavy loads,” he says.