Vitamin D and vitamin B12 deficiencies can cause tiredness, weakness, body pain, poor concentration, numbness, low mood, and muscle weakness when the body does not get enough nutrients or sunlight exposure. Poor diet, low sunlight exposure, digestive problems, a vegetarian diet, or long-term medical conditions may contribute to these deficiencies. Foods rich in vitamin B12 include milk, curd, paneer, eggs, fish, poultry, meat and fortified cereals. Vitamin D may improve with regular early morning sunlight exposure, along with foods such as eggs, fatty fish, mushrooms, fortified milk and dairy products. Protein-rich meals, nuts, seeds, green vegetables and fruits may also aid energy and recovery. Regular sunlight exposure for about 15 to 20 minutes several days a week may help improve vitamin D levels naturally. Diet alone may not be enough if the deficiency is severe, so supplements are sometimes needed for faster improvement. Consult your doctor for repeat blood tests and proper monitoring if symptoms continue despite dietary changes and supplementation.