I have a friend in Việt Nam who was always sick with flu or colds. In VN those maladies are called women's sickness because men very seldom get them. The difference is that men go about in short sleeve shirts in the tropic sun. There is no winter to speak of and the sun is sill high in January. I couldn't convince Trang to expose her arms at least to the sun because Vietnamese females hear from the day they are born that they must not let the sun touch their skin or hey will turn black and never get a husband. I supplied her with D3 and told her to take one daily. Her sniffles and cough etc stopped. I explained to her that those gelcaps ere just sunshine in a capsule and she started going out bare-armed and often hatless. That was in 200̀. She has not been sick since and she has convinced her sisters and cousins to do the same with similar results. We also discovered that her Manic Depressive condition which I had just brushed off as drama queenism went away. On research I find some neurologists and MDs who say that sunshine(vitamine D) is the only effective medicine against Depression.
I have become a fanatic Vitamin D/sunshine proselyte and have seen several people in the USA lose their long term depression.
Too much sunshine can be harmful to certain people. Skin cancer. But for those people who can tolerate large doses of sunshine, I agree that it picks up one’s spirit. BTW, your Home page is fascinating.