Common myths related to fitness and weight loss include the belief that spot reduction is possible, which asserts that targeted exercises can eliminate fat in specific areas. Another myth is that lifting weights makes women overly muscular, when in fact, it promotes lean muscle and enhances metabolism. Additionally, some believe that excessive cardio is the only path to weight loss, neglecting the importance of strength training and a balanced diet. Debunking these myths can lead to more effective and sustainable fitness approaches.