We conducted many model simulations to understand the causes of the damages of coronavirus (COVID-19) to lung tissue and constructed a diagram showing apparent viral reproduction, immune response and damage accumulation curves. We found that lung damages include virus-caused damage, tissue damage caused by immune responses and tissue damage caused by accumulated wastes. The virus-caused damage is proportional to the phase lag between the viral reproduction curve and the delayed adaptive immune response curve, while waste-induced damage is attributed to imbalance in removing viral, cellular and metabolic by-products. We found that treatment strategies should slow down viral reproduction and speed up immune response, and improve blood micro-circulation in the lungs. Consistent with the strategies, measures are taken to void direct lung infection, strengthen innate responses, promote immune responses, dilute viral concentration in lung tissue, maintain waste removal balance, protect heart and kidneys, control other infections, avoid allergic reactions and other inflammation, etc. We show that medical, dietary, emotional, lifestyle, environmental, mechanical factors, etc. may be simultaneously used to mitigate lung damages and prove that multiple factor health optimization method is magnitudes more powerful than a single factor treatment. Such a method does not depend on molecular specificity and can be used in parallel to antiviral drugs.