Better yet, get out and enjoy the sun and fresh air.
Do that, too, three miles every morning.
The trouble with sunlight is that while a healthy dose on lots of exposed skin will give you a boost, strangely it will take 2-3 days for that Vitamin D to work its way into your bloodstream. Plus, subsequent exposures will produce less Vitamin D, if you already have what the body considers to be a minimal amount.