Eating the following has been shown to help boost your immune system and can prevent illness and long term health issues: Vitamin C-rich foods, like citrus fruit and broccoli, Vitamin E-rich foods, like nuts and whole grains, Garlic, Zinc-rich foods, like beans, turkey, crab, oysters, and beef, Bioflavanoids, which are found in fruits and vegetables, Selenium-rich foods, like chicken, whole grains, tuna, eggs, sunflower seeds, and brown rice, Carotenoid-rich foods, like carrots and yams, Omega-3 fatty acids, found in nuts, salmon, tuna, mackerel, flaxseed oil and hempseed oil. 

Having a good sob is reputed to be good for you, so is laughter, which has been shown to help healing. Studies in Japan indicate that laughter boosts the immune system and helps the body shake off allergic reactions.