"As you get older, you need strength more than cardio," says Samantha Montpetit-Huynh, founder of Toronto's Core Expectations, a company focused on pre- and postnatal personal training. That's because your muscle mass gradually starts to decline over time, and it takes your metabolism down with it.

Since muscle tissue requires more energy to sustain itself, building muscle helps you burn more calories -- even if you’re just sitting on the couch. A 2007 study published in The American Journal of Clinical Nutrition found that overweight and obese women who participated in strength training twice a week for two years saw a significantly larger decrease in body fat than those who didn't.

But that’s not the only benefit to strength training.
"Strong muscles help support your joints and bones," says Montpetit-Huynh. "People who are strong don’t easily break anything." Several studies have shown that resistance training increases bone density, protects against fractures and reduces the risk of diabetes.

Concerned about bulking up? Don’t be.
Montpetit-Huynh says that's a myth: "You would need such a large amount of food and testosterone. You would also have to lift super-heavy weights." Sticking to more manageable weights and gradually increasing your repetitions will give you the muscle endurance you need for everyday life. (A little extra muscle makes carrying groceries a cinch!)

If you’re focused on weight loss, try this circuit of moves without any rest in between; your heart will be pumping before you know it.