A common mistake individuals make when trying to build muscle is overlooking the importance of nutrition. Many people focus excessively on their workout routines while neglecting their protein intake, which is crucial for muscle recovery and growth. Insufficient calories and macronutrient imbalances can hinder progress. Moreover, inadequate rest and recovery also play a significant role; muscles need time to repair and grow stronger. A well-rounded approach that balances training, nutrition, and recovery is essential for successful muscle building.