Most people exercise in order to lose weight faster. Actually, their goal is to lose to excess body fat faster. Well, here is some sad news. Losing body fat is a slow, long process. Frankly, to lose more than one pound of fat a week is a difficult task. Fortunately, there are plenty of other reasons why you want to be incorporating exercise into your daily life regardless of the fat loss benefits.

Let’s start with strength training first. The primary benefit is maintaining muscle mass while you age, and in the process maintaining your immune function as you age. Between ages twenty and forty, you will lose about 40 percent of your muscle mass, and then about 1 percent every year thereafter. The good news is that your body maintains the ability to synthesize new muscle as you age. You have the same ability to build new muscle up through your seventies and eighties as you did in your twenties and thirties. Although we maintain the ability to synthesize new muscle mass as we age, we have to combat the increase in the rate of degradation of muscle that occurs with aging. The most likely reason behind this muscle loss is an increased level of cortisol, which rapidly tears down existing muscle mass and converts it into glucose. This also happens if you follow a very low glycemic-load diet, like the Atkins diet.

Thus, you are going to naturally lose muscle mass if you take no steps to maintain it. You have to continually do strength training to keep a constant stimulus to induce the cascade of events that leads to the synthesis of new muscle mass. If a lifetime of strength training doesn’t seem to be your cup of tea, then consider that without enough muscle, you’ll get sicker more often. The reason? Your body stores all its amino acid reserves in your muscle cells including the amino acid glutamine—a critical component for certain immune cells called macrophages and neutrophils. During times of acute stress, such as an infection, your body secretes excess cortisol in order to break down muscle cells to supply adequate levels of glutamine to your immune system.

If you don’t have adequate amounts of muscle, then you’re not going to have adequate levels of glutamine in a crisis, and your immune system is going to suffer. This is one reason that so many elderly people die from infections shortly after bone fractures. When they have a major injury such as a bone fracture, their body breaks down what little muscle it has to release enough glutamine to help repair the bone. This leaves practically no glutamine reserves to fend off infections. Thus, these patients are far more susceptible to pneumonia, staph, and other infections that run rampant in the nursing homes and hospitals where they are often recovering. Strength training at any age becomes a great defense to ensure the adequate levels glutamine reserves you need for maximum immunity and for reducing silent inflammation. The result is maintenance of wellness for as long as possible.

Just as the unexpected benefit of strength training is maintaining proper immune function, the unexpected benefit of aerobic exercise is that it builds your brain. Aerobic exercise can improve your overall brain function by activating a hormone called brain-derived neurotrophic factor (BDNF) to repair and potentially trigger the development of new nerve cells in the brain. Just as muscle cells need amino acids from protein-rich foods to repair themselves and grow, nerve cells in the brain require a very specialized type of long-chain omega-3 fatty acid as a fuel source. This fatty acid, docosahexaeonic acid (DHA), is found in rich amounts in fish oil. The DHA in fish oil works hand in hand with BDNF to keep your neurons and brainpower primed over time.

For years it was thought that the brain couldn’t regenerate nerve cells. Now we know that under the right conditions, it can be done. The stimulus for that nerve growth is BDNF. Aerobic exercise stimulates the release of BDNF. BDNF is like a master mason, but in order to build the structure, he needs some bricks. The bricks for the building of new nerves come from having adequate levels of DHA in the diet. So if you want to remain sharp as a tack as you age, do daily aerobic exercise and take your fish oil.