According to EverydayHealth

According to, strength training, or weight or resistance training, is very beneficial to everyone. It is a way to benefit your heart, improve your balance, lose weight and help you to feel better. It is a physical activity that pushes muscle against resistance.
Lifting weights, pushing, or pulling puts weight on your muscles and by building up resistance to the weight, in time will strengthen the muscle and then you can add more weight or resistance. Using weight machines or free weights, a person can see how much they are lifting and adding. However, doing push-ups or sit-ups using your own body weight as the resistance.