I haven't been sick for 4 years. But I'm feeling the cold more these days than when I was in my 20s. I figure it's getting older, and being less active. I'm going to the gym regularly, and doing regular meditation and energy work. I'm a lot more conscious of my diet than I was when younger, which helps me a lot. I daily eat vegetables, which helps so much. And I minimize with aim to avoid almost all "processed" food, or food with preservatives, pesticides, etc. Eat a lot of home cooking, which is great.
Sometimes I have cravings for crazy stuff like McDonalds, and I just honor it. Nicotine, caffeine and alcohol are not healthy in general and not for me so I minimize them and plan to cut all eventually. I occasionally (fortnightly?) take vitamins and minerals as tablets. I occasionally take a variety of pharmaceuticals or ayurvedic or Chinese medicines that I have found work for me, and there are some things simple well tolerated things I take almost daily. I also am conscious of and tend to my microbiome. Also, when I feel some nasal blockage or possible infection, I'll flush my sinuses with salt water and add a bit of iodine solution. Sometimes I'll gargle iodine as well. I try to stay relaxed as much as possible and try not to let things stress me out. I try to communicate well, assert myself and do what matters to me.
I recently bought an air purifier for home, and I find it really matters a lot. Also I keep the house clean of dust etc. I sleep well, and my gut is regular. I brush my teeth 1 - 3 times a week, and floss 1 - 2 times a week. I have zero fillings. I feel I'm blessed with good health, which is awesome. I wasn't always so healthy. For the first 3 decades of my life I was sick a lot more regularly, like a normal person level.
I drink lots of water, more than most people. Recently I bought a copper jug and sometimes I leave water in the jug then pass it through a Brita filter. Other times I just boil the tap water, then Brita filter it. I love water. I rarely use products on my skin and hair and I try to avoid things with fragrances. Some of the Kiehl's stuff I like tho.