It’s true: Your immune system is challenged by the passing decades. Diversity among disease-fighting T- and B-cells declines; there are changes to your innate immunity — that is, protection provided by your skin, sweat and tears, and a general inflammatory response; and you develop inflammaging. Really, that’s what they call it! Inflammaging is the accumulation of inflammatory mediators in your tissue (oh, those random aches and pains).

But you can do a great deal to promote a more robust immune system as you age. You are never too young or too old to start accumulating the benefits of improved nutrition, increased physical activity, better sleep and less unmanaged stress.

So here’s our three-step plan to boost your immune strength as you age.

1. Move. Do a lot, but not more than two hours at a time. A new study out of the University of Birmingham in the U.K. shows that a consistent adherence to an exercise routine transforms your immune system. For this study, published in Aging Cell, the scientists looked at 125 adults 55 to 79 years old who’d maintained a high level of physical activity (cycling) for much of their adult lives and compared them with 75 age-matched older adults and 55 young adults not involved in regular exercise.

Although running marathons can cause a prolonged decrease in immune activity, the researchers found that the cyclists had more robust production of T-cells from the thymus (better ability to fight off infections) than inactive folks.

Your move: Build up to 10,000 steps a day and check out our book “YOU: Staying Young Workout.”

2. Relax. The second part of boosting your immune strength comes from reducing your stress response and increasing your quality and quantity of sleep.

Psychoneuroimmunology reveals that stress lasting a few days or more becomes chronic (say, from caregiving or unemployment), which interferes with T-cell responsiveness and dulls the immune system. The solution, say researchers in a study in the Annals of the New York Academy of Science, may be mindful meditation, which several studies indicate improves specific markers of inflammation, cell-mediated immunity and biological aging. Other stress-reduction techniques that produce improved immune response include progressive and differential relaxation as well as breathing and visualization exercises.

Your move: Daily 10 minute de-stressing routine.

3. Bite it. Your nutritional choices have a huge influence on your immune health because of their impact on your gut biome and on other bodily systems.

Your Move: Dodge the Five Food Felons (trans and sat fats, added sugars and syrups; any grain that isn’t 100 percent whole). Take 1,000 IU of vitamin D-3 daily; eat 7 to 9 servings of fruits and veggies a day. And, get your micronutrients.

According to Harvard Medical School: “There appears to be a connection between nutrition and immunity in the elderly. A form of malnutrition that is surprisingly common even in affluent countries is known as “micronutrient malnutrition.” That’s why you want to get enough zinc; selenium; iron; copper; vitamins A, C, E and B-6; and folic acid.

Mehmet Oz, M.D., is host of “The Dr. Oz Show,” and Mike Roizen, M.D., is Chief Wellness Officer and Chair of Wellness Institute at Cleveland Clinic. Email questions to youdocsdaily@sharecare.com.