It’s that time of year again. Everyone has a cold, the flu, a bug—whatever you want to call it, it’s all around us. You might feel like you need to keep yourself hidden from the world until it’s all over—but you don’t! There are things you can do to protect yourself from the common cold—and it starts by knowing exactly what you need to protect yourself from.

These are five of the top culprits that may be lowering your immune system—and what to do to make sure they don’t!

1) SUGAR

You knew I was going to start here, didn’t you? It’s hard not to hear about the dangers of sugar in your diet these days. And I personally know the havoc they can wreak on your body—sugar no longer has a place in my diet or my life!

Sugars—particularly of the refined variety—suppress the immune system by targeting cells that attack bacteria. To be clear, we like these cells—we need these cells to keep us from getting the dreaded winter bugs! But sugar kills them right off; killing off any chance that you might remain healthy right along with it.

“But holiday season is over!” you may exclaim. “I’ve cut back on the candy, cakes, and desserts!”

First of all, good for you! But I’ve got some bad news, too. High amounts of sugar can be hidden in a lot of other not-so-obvious foods: pre-made tomato sauce, protein bars, flavored yogurt, breakfast cereals, vitamin water, and so much more.

Added sugars can also be disguised by different names—61 different names, to be exact! So check your labels and look out for “sugar in disguise”: sucrose, high fructose corn syrup, barley malt, dextrose, maltose, and rice syrup . . . just to name a few.

2) STRESS

Okay, you probably know stress is bad for you. And, unlike sugar perhaps, I doubt you’re the biggest fan of it yourself. Long days at work, sick kids, visiting family—any and all of these things (and more) can cause stress in your life. And it’s not fun! But worse, it’s robbing your immune system of its full operating powers—it’s making you weak, too!

I’ll explain: When you encounter a perceived threat (like, your boss assigning a new project on Friday afternoon or your kid throwing up in the backseat in the middle of your four-hour drive to the in-laws), your hypothalamus—a tiny region at the base of your brain—sets off an alarm system in your body. This system prompts your adrenal glands—located on the top of your kidneys—to release a surge of hormones, including adrenaline and cortisol. Adrenaline increases your heart rate, elevates your blood pressure, and boosts energy supplies. Cortisol (also known as the primary stress hormone) increases sugars (glucose) in the bloodstream, and curbs functions that would otherwise be nonessential in a fight-or-flight situation. It alters immune system responses and suppresses the digestive system, the reproductive system, and growth processes. In other words, stress (unnecessarily) shuts your body down.

But there are quick fixes to stress, too! One easy way? Get a good laugh in your day! Laughing relaxes the whole body by relieving physical tension and stress—and it actually boosts the immune system, too. How funny is that?

3) TOILET TIME

Now, it’s time to get personal. We’re taking it to the bathroom—or more specifically, whether or not you’re going there enough.

Believe it or not, most of your immune system actually lies within your gut—approximately seventy to eighty percent of your immune tissue is located within your digestive system! The gut is often the first entry point for exposure to pathogens (bad bacteria) and viruses that can cause disease.

So what does that have to do with time logged on the toilet? Well, if you’re not going enough—or if you’re constipated—undigested food particles stay in your body much longer than they should. This provides a feast for those pathogenic creatures, allowing them to flourish and weaken your immune system.

Need help to get going? Eat foods that are rich in fiber, drink plenty of water, and take a good quality probiotic daily. You’ll be back to business in no time!

4) DRY AIR

You don’t have to live in one of the more pollution-infested areas of the world to know that our air is filled with viruses and bacteria. Luckily, our very own noses and throats are an excellent line of defense against the air we breathe—built to protect us against those nasty bacteria! They purify and humidify the air before it enters our respiratory system where the real damage can begin.

How? Well, the main components of our built-in defense mechanism are a layer of tiny hair-shaped structures called cilia; they live inside our respiratory tract and have a thin membrane of mucous that covers them. Airborne pollutants are captured by this sticky mucous membrane and removed from the air.

But here’s the problem: If the air we’re breathing is below relative humidity over a prolonged period of time, the mucous membrane layer dries out—which damages our cilia! That, in turn, inhibits our ability to filter pollutants from the air we breathe and leaves us susceptible to infections.

(Now it makes sense why you always get sick during the winter, right?)

Here’s one simple tip to combat the effects of those dry winter months: Put a humidifier in the rooms you spend the most time in—especially your bedroom! A good humidifier will put moisture back into the air, allowing that helpful mucous membrane to stay lubricated and do their job.

5) YOUR THOUGHTS

Despite what you may think (or because of what you might think, as I’ll soon argue!), it’s true—the emotion behind your thoughts can affect your odds of getting sick. And I’ve got the research to prove it! A 2003 study linking “emotional style and susceptibility to the common cold”, found that there is indeed a link between happiness and a stronger immune system. Conversely, those who experienced more negative emotions were more susceptible to disease.

In the experiment upon which the research findings are based, 350 adults volunteered to get exposed to the common cold. (Crazy, I know!) But before exposure, researchers called them six times in two weeks and asked how much they had experienced nine positive emotions (e.g, feeling energetic, pleased, and calm on that particular day). Then they found that, after five days in quarantine, the participants with the most positive emotions were less likely to have developed a cold.

Though this seems like the simplest tool of them all, it’s often the hardest—and most easily forgotten! Try to keep yourself in a more positive state a mind by adding a daily routine of meditation, a walk outside, or anything at all that makes you feel happy and keeps your thoughts happy, too.