What long-term steps help with severe vitamin D deficiency despite outdoors?

[Stella69]

My recent annual bloodwork revealed a surprisingly severe vitamin D deficiency, which explains my persistent fatigue and general achiness, but I'm confused because I spend a fair amount of time outdoors and consume dairy regularly. My doctor prescribed a high-dose weekly supplement, but I'm curious about the underlying cause and the best long-term strategy beyond just taking pills. For others who have addressed this, what lifestyle or dietary changes made the most significant impact on maintaining your levels? How do you navigate the balance between sun exposure for natural synthesis and skin cancer concerns, and are there specific co-factors or absorption issues I should discuss with my doctor?