Conventional wisdom associates travel with illness. This is a shame since travel is supposed to be associated with opportunities and adventure.
There are a number of good reasons why travel is associated with illness. For one, it tends to be stressful to prepare for travel. Two, you are often put into close quarters with people who may be ill, about to be ill, or who simply have different flora which are pathogenic to you. Three, you may need to eat food which does not agree with you.
Four, people do not hydrate well enough when they travel. They are preoccupied, and do not want to take the time to go to the bathroom, either on a road trip or on an airplane. This is a big mistake, not only from the point of view of hydration, but also from the point of view of urinary tract infection and thromboembolic disease like clots in the leg or the lungs.
So how to ensure that you stay well for travel ? These are supremely unglamorous and commonsensical recommendations. First, prepare well in advance for your trip. This includes getting any required vaccines far enough in advance especially if you are going to any high-risk areas. Give your coworkers lots of advance notice, so there are no snafus. Give yourself lots of time to thoroughly prepare, and this will lower stress levels. Lowering stress is key to preventing illness, since stress weakens the immune system.
Moderate regular exercise dramatically strengthens the immune system. No surprise here. But of course this has to be month in and month out to make a difference. But you're going to do that anyway since you want to look good on the beach, right ?
Wash your hands with soap even more frequently on trips. Try to keep your hands away from your face. Keep hand sanitizer handy. Most of it makes me gag but you can get nice stuff with essential oil that is just as effective.
On the assumption that you will pick up germs, make sure and have good mouth hygiene, brushing and flossing as usual. For extra credit, use a peroxide mouthwash before bed to chase away that hint of a sore throat.
Hydrate well, avoid alcohol and bring your own snacks wherever possible. Don't be afraid to get up and walk a bit on the plane, or to stop and go in the bushes.
When you eat out, order wisely. Don't be afraid to ask your waiter or chef to alter your dish. After all you are paying for it.
Finally schedule a long enough vacation. If it is too short you will be tempted to overdo it. No one has ever seen Rome in a day. Don't be that gal who arrives back at work and says, "I'm so relieved to be back at work so I can get some rest."