Alternatively you could wander outside in shorts for a few hours?
Most Vitamin D comes from the effects of the suns’s ultra-violet radiation on our skin. Problem being that in the UK, much of Europe and the USA, we live at too northerly a latitude, where only summer sunshine is strong enough to be much use. This is made worse by the modern low sunshine exposure since we now live skin-cancer fearing, car/home/office-bound lives. Studies suggest we are on average around 60% deficient in Vitamin D3, it’s better if your skin is fair but worse if it is darker.
Vitamin D3 improves mood, maintains calcium balance (helps avoid osteoporosis), reduces cancer risk, boosts the immune system, helps with insulin secretion, regulates blood pressure and may reduce risk of autoimmune diseases like diabetes, multiple sclerosis and rheumatoid arthritis. It’s easy and relatively cheap to buy some Vitamin D3 oil or pills, you only need a couple of drops of the oil each day to gain all those benefits and enjoy “sunshine happiness”, even on cloudy days.