Eating right and exercise are important to your health, but so are rest days, according to an expert at Baylor College of Medicine.

"It's not ideal to work out when you're sick because you're stressing your system out," said Dr. David Green, assistant professor of orthopedic surgery at BCM. "The same thing is true after a recent surgery; your body is trying to recovery from the surgery."

Whether or not you should work out or with how much intensity depends on the extent of your illness or recent surgery, said Green.

If you still want to stay active, consider using simple things such as arm bands for gentle exercises, but stay away from heavy aerobic exercises, he said.

"If you're experiencing some joint or muscle pain, it's your body's way of telling you that you're overdoing it, so you should back off. Try using a heating pad or taking anti-inflammatory medication to help with the pain," said Green.

In general, be sure to have some type of snack about an hour before a workout; do not try to exercise on an empty stomach. If you're over the age of 40 and just starting heavy exercise for the first time, be sure to consult with your physician first. Also consult with a physician if you've had any respiratory, cardiac or joint issues in the past.