You spend months planning the perfect vacation. You pick a destination, save your pennies, and remember to update your passports — seriously, check those passports — only to fall sick five days into your trip. What a drag. I've been on a lot of trips and I've been sick on a few of them when I ignored my own advice. Avoid spending days holed up in a hotel room while your family has all the fun and eats all the food by following these tips to stay healthy while …