Your body is a machine. That does not mean you are ready to take on the Terminator, no matter which timeline we are in. It means your body consists of interdependent groups of items (organs), forming a unified whole (Merriam-Webster, 2020). Your immune system is no different. It works when the interconnected parts and systems are working. If one part breaks down, the system can lose efficiency and find itself in trouble.
System maintenance
Due to our internal systems' complexity, there isn't one thing you can do to maintain a healthy immune system. Like your car's mechanical workings, you have to maintain all of the parts to ensure it is working properly. Changing your tires will only get you so far if you ignore your filters, oil, belts, etc. Fostering just one part of a system, whether it's your car or your body, can lead to groaning and possibly a complete loss of operation. Because of the intertwining of all of our systems, the effects of diet, exercise, age, and stress all play a role in how well our bodies perform.
Help your body, help you
Your body is constantly under attack from viruses, aging, and environmental factors you can't control. Give your body a fighting chance (literally) to ward off sickness by choosing healthy habits. Most of these strategies are free, and all of them benefit your body.
Don't smoke or vape
Eat a healthy diet
Exercise regularly
Maintain a healthy weight
If you drink alcohol, drink only in moderation.
Get adequate sleep.
Washing your hands frequently
Manage stress
Fight the good fight
Overall, your immune system does an incredible job of defending you against disease-causing microorganisms. But no body is perfect. Even with strong defenses, a germ can successfully invade and launch an attack campaign, making you sick. However, continuously following a healthy lifestyle will significantly improve your body's ability to fight off diseases and keep you and your body going.