How do i manage never to get sick? my immune system is really good? is it cause i take multi vitamins plus c ones too?

Healthy: Has more to do with your genetic make up than anything else. If you live a healthy life style and eat a well balanced diet additional supplements and vitamins probably don't much.

Good genes: Have a healthy diet, exercise 30 minutes/day, drink plenty of water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. For nutrition: http://www.choosemyplate.gov/. Wish you good health!