Good health is a matter of choice.
Only plain, wholesome food should be eaten.
Overeating, intoxicants, and stimulants avoid.
Drink plenty of water...nature's remedy.
Have plenty of fresh air in the bedroom.
Eight to nine hours of sleep every night.
Always breathe deeply in the open air.
Look to the cleanliness of body and mind.
Take regular outdoor exercise.
Heed sanitation, sobriety and safety first.
Look upon life with faith, hope and good cheer, and keep the mind and heart free from hatred, jealousy and revenge.
Source: The Stevens-David Company, Chicago, 1918
I think this should still apply for today. Although, I may have a problem finding the "fresh" air.