You've got to use daylight in moderation.
I run 3 days a week and am often out walking or gardening and was vit D deficient despite this. There is genetic variation in the ability of skin to synthesise vit D whatever the skin colour. I am pretty damn pale - as you'd expect of any Anglo dermatologist or ex-dermatologist. Also, the ability to synth vit D will diminish with age especially in women.
You don't need to buy into the mystic benefits of vit D. I don't. But you need normal vit D levels for bone health - again, especially as you get older. Having broken maybe more than my fair share of bones over the years - fingers, toes, ribs, comminuted fracture dislocation R ankle - I would like to keep my bones in as good shape as possible.
All that said, I was out running this morning on Mt Taylor, and the light, the blue sky, the 18C, the breeze...fantastic.