For me the sun does it. Not right now during a heat wave, but in general, year round, getting the sun in my eyes especially early in the morning, immediately puts me in a good mood for the rest of the day.
I know my income and QoL would be better living in nordic countries but I just can't stomach long periods of gloomy weather no matter the amount of Vitamin D pills.
Seriously though, I come across people now and then who "don't like sunshine" and i feel like an explorer who's just encountered a strange new civilization; this attitude is completely alien to me and my instinct is that there's something wrong with them. I used to wonder if I was just imagining things and over-selling it because I live in a pretty rainy place (Vancouver), but then I worked in California for a couple of years, and nope, it really makes a huge difference to my energy levels and general outlook. Going back to looking for jobs in sunny places again soon.
I had an apparently-unusual problem, whereby my system seemed to react poorly to the large-dose monthly Vitamin D pills. The problem was hard to pin down, other than a repeated sense that everything (mentals, sleep, digestive system, ...) suddenly sucked, starting, on each occasion, with the taking of a Vitamin D pill.
So I swore off them, and rely upon the natural (sun) source instead.
Vit.D is not a magic cure for chronic/severe conditions, unfortunately - alone, nothing is - but it services critical physiological functions, without which, everything is that much harder.
Well according to this link [1] the LD50 for zinc is close to 3 g/kg body weight, more than 10-fold higher than cadmium and 50-fold higher than mercury.
If this is wrong for humans, then the US Govt is certainly not giving a toss about its unqualified statements!
Stomach acid dissolves metallic zinc, producing zinc chloride, which is a corrosive product damaging the stomach lining.
And if the British Govt was really bothered about our health, it wouldnt allow very hard water with lots of lime scale that inhibits zinc uptake, and if the medical experts were that bothered, they would be checking our diets, but they dont, just like they dont bother about tobacco products.
Some many expert criminals its hard to know who to listen to.
I know my income and QoL would be better living in nordic countries but I just can't stomach long periods of gloomy weather no matter the amount of Vitamin D pills.
Sample size one.