Age and gender have nothing to do with whether weight training should be a part of your exercise routine. One of the best predictors of health later in life is strength and lean muscle mass. It's also the best way to handle everything life throws at you. Weight training would be optional if we never needed to lift more than our own body weight or never moved faster than a walking pace, but that's just not the case. Someone who is capable of squatting just 30lbs is much more prepared to carry groceries up a flight of steps than someone who doesn't practice weightlifting. Practice builds strength, coordination, and makes us more resistant to getting hurt. It's not a question of if you should lift, but how to safely incorporate it into your workouts.