It's never too late to start! I turned 78 in December and been in weight training since my late teen age years. As you get older the change of routine should be lighter weights and higher repetitions. In addition, listen to your body and don't force movement that is painful or may damage past injuries. As we age it's not how much you can lift it's how well can you lift the weights that you can handle for 15 - 20+ reps. And good weight training, at any age, is to not work the same muscles every day - give them a break between workouts. I find that at my present age I have more strength and energy if I have 2 days off between my weight training. And don't forget the cardio!