To make the most of your vacation, plan your sleep
times accordingly so that you can maximize your fun during
your waking hours. Spend time outside in the sun, walk, jog, cycle, swim, and relax! If possible, remember to give yourself a day or two to wind down after you come back before you go back to work.
Even if you don't suffer from any problems during your trip, many ear and sinus problems occur AFTER your return trip, usually aggravated by the return flight.