Signs that someone may need to adjust their workout plan include persistent fatigue, lack of progress, or the onset of injuries. If an individual consistently feels drained after workouts or struggles to meet their performance goals, it may indicate that the routine is too strenuous or improperly structured. Additionally, a lack of motivation or boredom with workouts can signal the need for a change. Regularly evaluating one's fitness plan and adapting it to reflect personal progress and challenges is crucial for continued improvement and enjoyment.