Common mistakes when starting a fitness program include setting unrealistic goals that can lead to early burnout or disappointment. Many individuals also overlook the importance of proper warm-up and cool-down routines, increasing the risk of injury. Inadequate knowledge about exercise form or technique may lead to poor results or injury. Additionally, neglecting nutrition and recovery can hinder progress. Creating a structured plan that balances exercise, recovery, and healthy eating, along with consulting professionals when needed, can foster a successful fitness journey.