9. Get some sunshine
Vitamin C, Vitamin E, and Vitamin B6 are all important- but so is Vitamin D. During the winter it may be hard to open the door and force yourself out into the frozen tundra, but it is necessary for a healthy immune system. Just 15 to 20 minutes of sunlight everyday will give you the dose you need. But be careful to not overdo it- too much could give you sunburn and increase your risks of skin cancer.