When you exercise, you don’t just get more impressive on the outside.

Some of the most significant payoffs of exercise are elicited beneath your appearance; specifically, the health of your cells is improved. By considering these benefits, we can see the reasons behind making a daily investment in exercise.

One benefit of physical activity is it enhances your defense against chronic disease.

In order to understand the means by which exercise deters disease, it’s necessary to realize problems derive from unhealthy cells. Cancer, for example, is an uncontrolled growth of abnormal cells. Heart attacks, atherosclerosis — hardening of the arteries — and strokes often occur as a result of foam cells forming plaque in blood vessels.

If you want to be the happiest and healthiest person you can possibly be, you need to create an internal environment that promotes the happiest and healthiest cells possible.

The health of brain cells plays a significant role in your functionality. For those who exercise regularly, neurological function has been shown to improve, memory is enhanced and feelings of happiness have been shown to increase.

“[Aerobic exercise] is pretty well linked to doing things like decreasing chronic anxiety [and] decreasing chronic depression,” said Victoria Books, instructor of kinesiology and physical education. “There’s some research that shows that [exercise] can work as well as medications for managing those things.”

Let’s take a look at the science behind this. Growth factors, like the brain-derived neurotrophic factor and IGF-1, an insulin-like growth factor, are key components for cognitive health that are increased during exercise. Each is required for neurons to communicate effectively.

“[Brain-derived neurotrophic factors] and IGF-1 may reduce brain atrophy,” and “BDNF is known to be associated with neurogenesis and increased survival of neurons,” according to a 2013 report by Integrative Medicine.

The endorphins released as a result of exercise have also been shown to improve your mood. Additionally, the neurotransmitters stimulated by exercise help reduce symptoms of depression. This combination is a recipe that yields approximately one happy you.

The immune and lymphatic systems are also improved by physical activity.

Exercise promotes excretion of waste products, decreases stress levels and improves blood flow, all of which help your cells win the war against infection.

Your respiratory system is enhanced with exercise, as well: Lung capacity increases with aerobic exercise.

Even your digestive system can chew on some benefits. Individuals who engage in physical activity have been shown to experience a decrease in digestive problems — such as irritable bowel syndrome — according to a 2011 study by the American Journal of Gastroenterology.

“There is no real process in the body that isn’t aided by exercise,” said Mitchell Howie, certified personal trainer at the Recreation Center. “Your thyroid will produce more stable levels of hormone, … your digestive system will become more efficient, your heart will become more efficient, you’ll sleep better [and] you’ll get more blood to the brain. …Overall your entire body just benefits from it.”

Allow the health of your cells to motivate you to exercise. If you get in the gym consistently, physical results will only be the beginning of your rewards.