Why do some people never get sick regardless of wind, rain or shine? American health website WebMD revealed their health secrets.

1. Get physical

Just one session of rigorous exercise a day can increase blood circulation and allow the white blood cells in your body to fight infections effectively.

2. Watch your breath

Using a mouthwash every day reduces the risk of gum disease such as gingivitis. As gum disease has been linked to diabetes, it is another reason to gargle and rinse, WebMD reported.

3. An apple a day

There may actually be a grain of truth to this old adage. Red apples have a natural antioxidant - quercetin - which may help give an immunity boost to people under stress.

4. Vitamins rule

Remember to take a good mix of vitamins, especially the often forgotten vitamin D found in eggs and milk. Vitamin C may boost your immune system, though it is a common misconception that it prevents colds.

5. Wash your hands

During the cold and flu season, remember to wash your hands more often, as you are in contact with all sorts of pathogens lurking on the surfaces of things such as door knobs, stair railings and phones, said website WebMD.

6. Mind over matter

Having a positive attitude towards your health may make you more resistant to illness. Being positive and refusing to submit to illness increase nitric oxide levels that improve circulation and immunity. People with a more positive outlook are also less likely to catch colds.

7. Get your 40 winks

A good night's sleep, ideally eight hours, allows your body to produce more melatonin which improves your overall immunity.

8. Learn to relax

If you are a worry wart and do not know how to relax, you may be pushing yourself towards illness.

When under constant stress, the body produces higher levels of cortisol and epinephrine. These stress hormones suppress the immune system and weaken the body.

9. Holistic healing

Meditation and breathing exercises can help calm the mind and body and have been linked with the production of flu-fighting antibodies, says website WebMD.

10. Chat up a storm

Extroverts and people with diverse social networks are less likely to develop colds, says a study by American psychologists.

» Next: 4 natural ways to fight the flu