As all-natural and side-effect free as you can get, sleep can also be pretty hard to come by (yeah, yeah, understatement of the year, we know). Still, it's so important: Sleep deprivation has been scientifically linked to decreased immune system function, according to WebMD, so getting enough rest really can help to keep you as healthy as possible.

When everybody's cooped up inside hiding from the elements (and you haven't had time to make it to the gym since), it can be tough to make sure your family is getting enough exercise. But finding ways to squeeze a little cardio into your day can really pay off during flu season: Researchers at the University of California-San Diego of Medicine found that as little as 20 minutes of exercise can have anti-inflammatory effects that strengthen your immune system, reported Reader's Digest.

This one probably isn't practical for young kids, but The Daily Mail reported that researchers discovered that taking a "hot-to-cold" shower — i.e., turning the water temp to cold for the last 90 seconds of your shower — can actually boost the body's number of disease-fighting white blood cells. Who knew?

Look, we're not saying you have to go on a cleanse or anything, but according to Prevention, it's true that the excess refined sugar and polyunsaturated fats in junk food can keep your immune system from functioning as well as it should... so you should avoid processed stuff as much as possible, and make sure your kids do the same.

Good news for crudité fans: Beta-carotene, which is the stuff that gives fruits and veggies like carrots and peppers their orange hue, is a powerful antioxidant that's been shown to improve immune system function and fight free radicals. One word of caution: Because beta-carotene converts to Vitamin A in the body and too much Vitamin A can be toxic, you'll want to be careful about nutritional supplements like pills and drops. Luckily your body will know to convert only what it needs, explained The University of Maryland Medical Center, but you can never be too safe so get your extra beta-carotene straight from food sources as much as possible.

We all kid around about how stressed we are all the time (because it's better to laugh than cry?), but what stress can do to your immune system is no laughing matter: Dr. Andrew Goliszek, professor at North Carolina A&T State University wrote on Psychology Today that when you're stressed out, the brain sends defense signals to the endocrine system, which then releases hormones designed to prepare us for emergency situations. Unfortunately, these fight-or-flight hormones can also severely repress immune function, with some experts claiming that stress is the cause for as much as 90% of all illnesses (including cancer and heart disease!).

There's been a lot of buzz about the benefits of probiotics (found in yogurt and other fermented foods) in recent years, and with good reason, too: Studies have shown that probiotics can help to regulate the immune system and reduce inflammation. In addition to adding probiotic-heavy foods into your diet, you might also consider trying some high-quality supplements (usually found in the refrigerated section of your natural foods store).

There's a reason why zinc is added to so many cough drops and lozenges. This near magical mineral plays an important (and scientifically proven) role in balancing the immune system. The amount of zinc you should be taking depends on your age and sex, as well as your diet, and this handy guide from the National Institute of Help can help guide you, but you should also ask your doc before starting on any kind of daily supplement regime.

It's not just for keeping vampires away: Research has shown that eating garlic can increase the number of T-cells in your bloodstream, reported Everyday Health, which is a big deal because T-cells are for virus-fighting (and the flu is a virus). Unfortunately, cooked garlic isn't quite as powerful as raw garlic (or garlic in capsule form). Try blending a few fresh cloves into hummus or guacamole!

You know the drill: Washing hands, sanitizing frequently used surfaces/objects, not touching your face... it's all basic hygiene flu prevention stuff you've heard a million times. But we're saying it again anyway, because it's such a big deal (and, after getting a flu shot, the second best way to avoid the illness).

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