1. Biting your nails. Putting your fingers in your mouth and biting your nails is unsanitary and can expose you to all sorts of bacteria, viruses, and infections. It's also not good for your teeth.
2. Eating at your desk. You're typing on a keyboard that's most likely covered in germs, and then putting food in your mouth. Not a good combo.
3. Smoking. This one should be obvious. If the cancer risk alone isn't a good enough reason, smoking can decrease your immune function, making you more likely to catch the flu, a cold, or pneumonia.
4. Not changing your sheets. Dust mites love your nice, warm bed as much as you do. And even though dust mites themselves are harmless, their droppings and body fragments can cause colds and trigger asthma symptoms.
5. Not getting enough sleep. According to BetterSleep.org, about half of Americans say they don't get enough sleep, which is between seven and nine hours a night. And when you DON'T sleep enough, it decreases your energy levels and makes you more susceptible to illness, since your cells can't fully recharge while you snooze.
(Bustle)