Vitamin D is essential for calcium metabolism, bone formation, and growth. It also helps remove calcium from arteries and reduces cancer and illness risks by improving immune response. A 30-minute sun exposure at 9 AM can generate 10,000-20,000 IU of vitamin D, equivalent to cod liver oil. Sunlight exposure during outdoor work may help explain why laborers live longer, due to vitamin D and physical activity. Vitamin D is a powerful natural antidepressant, as sunlight triggers the brain to release serotonin. Getting moderate sun exposure can help people feel happier and live healthier lives with fewer medical issues.