Apologies in advance for the run-on dabbler-classic essay.
Your immune system is your friend, must treat it so.
I do wash my hands, with soap, but I almost never disinfect anything.
The stuff you’d use to disinfect things is often more harmful, in repeating doses, than whatever to which you’d be exposed.
I have a chlorine filter on my drinking water and on my shower/tub.
Chlorine’ll kill you, slowly. If you use bleach to swab the decks in the lavatory then get out of there fast and air it out well before you use the room.
I avoid antibiotics unless absolutely necessary (e.g. dental surgery or staph infection).
If you have a staph infection then they can save your life. Other than that they can beat up your immune system to the point that it will roll over every time something comes along, and you need antibiotics to get you through and and every mundane infection.
I eat salads and other raw foods that have helpful immune system enzymes.
I take vitamins B and C and D supplements and a few others.
D is especially helpful for the immune system.
Propolis, especially in a non-alcoholic medium, is good for immune system support.
I’m far from holy about what I consume. I am a vegetarian but I drink alcohol and eat pizza.
Just get a salad or some raw foods or some close-to-nature food in there often enough to keep your digestive system alive. Cooked food is dead. Mix it up with some live stuff like sprouts to help you get whatever nutrients you can out of the rest of the stuff you put in your mouth.
When I do get sick (happens every few years or so, I’ve taken two sick days in the past six years) I take a supplement called “Well-Max” that is a bunch of immune system support herbs plus some cayenne pepper heat.
Let a mild fever run its course. It’s good for you and helps get rid of what ails you. Do some mild stretching as the fever breaks to help the toxins out of your system and avoid them settling into your muscles (achy!).
Nasal irrigation is a god(ess)send if you get some head cold thing going on. Look into it. Blowing your nose is a pale example of the clarity possible with a good nasal irrigation procedure. Nobody needs bus exhaust stuck up in their head. A bit of sea salt and a neti pot can do you more good than a case of DayQuill.
When you get more used to it you can do it regularly in the shower w/o the salt. Practice before you try that.
Drink a lot of water, especially in environments where the air is heated or cooled and there is little moisture in it. if there is any heat on keep a humidifier going in your sleeping space at least. Your nasal passages and lungs will thank you. Put one in the living room too if you can.
This above might sound hippy-dippy airy-fairy but I almost never get sick any more. Up until I was in my mid-20’s I used to be on anti-biotics a few times a year for rhinoviruses or an infected this or inflamed that. Since then, the one time I was seriously sick in the past few decades was a time when after a month in Tibet I got food poisoning at the end of the trip. I was in Kathmandu when I let my guard down and had, for no good reason, quit taking a bit of propolis daily (which I like to do when travelling but when at home I don’t take daily). I had a fever over 101 for about five days. That was transcendental but not at all any fun.