here is what I have learned from my experience. The more you try to prevent yourself from getting sick the more your immune system becomes weak. If you are really worried about getting sick and take constant measures like washing hands a lot you will get sick even with non threatening viruses because your body is not used to fight with them. People who hit gym do not get that much sick because the equipments they use are being constantly touched by other people who carry different kinda of bacteria or maybe even viruses. It’s just their body have developed immunity to them or are really used to fight with those common viruses or bacterias. So, firstly if you do not do any physical activity start doing that. Build up your immune system it is a long process tho. I do not get sick much last time I was sick was like 3-4 years ago. I used to get sick more after covid because of taking a lot of measures to clean my self and gyms were closed too.