How to Stay Healthy While Traveling

It's flu season, and Covid is still making the rounds, and there's now some new terrible respiratory thing (respiratory syncytial virus) out there. All of those things, including just a regular cold, suck. If you're traveling, there's a good chance of getting sick, so you may want to stay vigilant. 
I used to get sick any time I went on vacation, but I've since learned how to stay healthy on all my trips, including while flying. If you're worried about getting ill and ruining your whole vacation,...