"If you want good health, a long life and to feel your best well into old age, the most important thing you can do is strength-training," Dr. Brett Osborn told us.

Osborn is the author of Get Serious, A Neurosurgeon's Guide to Optimal Health and Fitness.

"Our ability to fight off disease resides in our muscles," Dr. Osborn explained. "The greatest thing you can do for your body is to build muscle. Muscle is all protein, nothing but good for you!"

"Some fat is visceral fat - it's stored around the organs and it's even more dangerous than the fat you can see," the expert went on to say. "People who look thin may actually be carrying around a lot of visceral fat." 

So, what workouts does Dr. Osborn recommend? "Back to basics," he says. "These five exercises are the pillars of a solid training regime:"

The squat. Standing erect with a heavy load on your back and then repeatedly squatting down will stress your body in a good way -- forcing it to grow more muscle.

The overhead press. This activates the shoulders, arm extenders and chest. From the planted feet into the hands, force is transmitted through the skeletal system, stabilized by numerous muscular structures, most importantly the lower back.

The deadlift. This centers on the hamstrings, buttocks, lumbar extensors and quadriceps, essentially the large muscles of your backside and the front of your thighs. 

The bench press. Mostly targets the chest, shoulders and triceps; it's very simple - trainees push the barbell off the lower chest until the arms are straight. This motion stresses not only the entire upper body, but also the lower body, which serves a stabilizing function.

The pull-up / chin-up. A pull-up is done when hands gripping over the bar; a chin-up is where hands are gripping under the bar. "It's also been called a "man's exercise, which is nonsense," Dr. Osborn said. "There are no gender-specific exercises."

"There are no secrets to a strong and healthier body; hard work is required for the body that will remain vital and strong at any age," Osborn told us. "Always practice proper form and safety. Otherwise, the result will be the opposite of your goal, an injury."