Sunlight through windows such as in the office or in your car filters out most of UVB radiation, what you get is UVA radiation which decreases vitamin D. What you want is direct sunlight UVB to increase D, UVA is more responsible for skin cancers without the UVB.
Roughly half the population are D deficient. If you've not already had it tested ask for a 25(OH)D or 25-hydroxy vitamin D blood test. If you are deficient supplement with D-3 not D-2.
Anyone taking D3 and or calcium should be taking K2 as well. It is a co-factor of D3, working with it to tell the body where to deposit calcium so it doesn't end up in places like joints, blood vessels, and organs.
Vitamin K2 helps calcium to go to the right places. It directs calcium to go into your bones and teeth instead of your arteries.
Deficiency in K2 causes calcium build up in the arteries and valves. It also attaches to plaque. This can cause hardening of the arteries, heart attacks and strokes.
MK-7 is a type of K2 and is the most biologically active form of K2 to buy for health.