Why do you say this? 

Slightly tanned skin from sun exposure can be quite healthy due to the production of vitamin D.

1. Vitamin D Synthesis: When your skin is exposed to ultraviolet B (UVB) rays from the sun, it synthesizes vitamin D, which is essential for numerous bodily functions. Vitamin D helps in calcium absorption, promoting bone health and preventing conditions like osteoporosis.

2. Immune System Support: Adequate levels of vitamin D support the immune system, helping the body fight off infections and diseases more effectively.

3. Mood Enhancement: Sun exposure can improve mood and reduce the risk of depression due to the release of endorphins and the regulation of melatonin production, which affects sleep cycles.

4. Cardiovascular Health: Not 100% sure how true this is, but I read a few studies that suggested vitamin D may contribute to heart health by influencing blood pressure and reducing the risk of cardiovascular diseases.

I’m sure there are more points I could add, but these are the ones that come to mind first. 

Obviously anything excessive, like excessive sun exposure can increase the risk of skin damage and skin cancer, but there is for sure a balance between benefiting from vitamin D and wrecking your skin from 24/7 sun exposure your skin.