Indeed, good food is important. Also, don't be overly clean & don't over-dress. I'm not saying you should stop washing and sit naked in the snow but don't use all those desinfectants on everything, don't worry too much about eating a cookie or snack without washing your hands, and don't always bundle up completely when you're only going outside for a minute to grab your mail or take the garbage out. All these little things keep your immune system (& your own body's internal heating system) active, without overloading it. People who are too clean have little to do for their immune system so that if they do come into contact with anything, their immune system has to start up from almost zero and takes longer to respond. Or it can over-react -that's why so many children who grow up in ultra-clean households have allergies.
I know there was a reason I'm not the cleanist person in the world, and wear shorts and teeshirts in the dead of winter.
Regular exercise as possible (walking, swimming , push ups) A GOOD diet (limmited sugars, limmited fats, lots of fruits and veg) A good attitude hugs.
