I've been using dminder religiously since reading an article about how chronically low everyone's vitamin D is which means sunscreen can be net harmful[1] and getting tested to confirm I was dangerously low.

I'm in Dallas, TX which has a reasonable window of about three hours in the middle of every day where the sun is high enough to shine a substantial amount of vitamin-D-producing UVB rays. Even so it takes conscious effort to schedule an hour outside in minimal clothing and it's hard to do when it's cold and doesn't work if the weather is overcast.

In the winter I'm only able to get vitamin D from sunlight maybe once a week.

Now I take vitamin D supplements[2] and I'm experimenting with UVB bulbs made for lizard terrariums.

1. https://www.outsideonline.com/health/wellness/sunscreen-sun-...

2. Vitamin D supplements are much cheaper if you get a pill maker, empty pill shells, and a bulk bag of vitamin D powder: about 5¢/50k IU pill which is a week's dose.