Feeling worn out or "old" may begin at any age, depending on genetics, lifestyle, and health. Many people in their 30s to 40s report feeling less energetic, particularly if they have poor eating, exercise, or sleep habits. Fatigue can be accelerated by long-term stress, medications like thyroid imbalance, and vitamin shortages like B12 or D. Hormonal changes in midlife, such as low testosterone or perimenopause, also have an impact on energy. Some people use wakefulness-promoting drugs, such as Modvigil 200, to feel more awake for a short time, but long-term energy comes from getting enough sleep, eating a healthy diet, exercising frequently, and taking care of any underlying health conditions.