Dr. Ruth Sorotzkin, a family physician at Saint John's Health Center, says trying to pretend you're not really sick can only make you sicker.
"It can prolong you getting better from either a cold or the flu," said Sorotzkin.
Experts say many people don't recover because they can't sleep. One study found sleeping less than seven hours a night almost triples your risk of getting a cold in the first place.
Something else people don't do is drink enough fluids. You may think you're drinking enough juice and hot tea, but doctors say when you're sick, you have to drink more than you usually do. But one thing you don't want to drink is alcohol.
"Alcohol dehydrates our bodies even further. It actually does not promote better sleep, and maybe to some extent, lowers our immune system," said Sorotzkin.
Avoid cigarettes. Smokers get more colds than nonsmokers, and their illnesses usually last longer.
Also, don't overuse nasal sprays.
"They work for very short term, and if you use them for more than a few days, very easily the body becomes hooked on them and they cause a rebound, so to speak," said Sorotzkin.
Remember to take the time to de-stress. High levels of stress hormones can derail your immune system, leading to more sick days.