Diet: Try to create a healthy menu for yourself, which combines food that strengthens the immune system such as foods rich in Vitamin C.  You can read about this in various sites dealing with healthy eating.
 

Sleep: Try to maintain balanced sleep, both in terms of the number of hours you sleep and their dispersion throughout the day and night. Our body needs a balance and cycles of rest and awake activity.
 

Exercise: Integrate physical activity into your routine.  If you find yourself in isolation, you can use YouTube to find various sports and exercise activities which can be performed in any room.