This investigation details the story of Diego, a novice Mexican teacher in secondary school. The story uses a life history approach and describes Diego's process of overcoming mathematics anxiety. Diego experienced mathematics anxiety due to his lack of mathematical knowledge. Having detected this situation, the researchers coached him, focusing on his emotional and mathematical knowledge. After this coaching, Diego managed to overcome his mathematics anxiety and enjoyed teaching mathematics. Cases like Diego's are common among novice teachers in Mexico; they are more likely to experience negative emotions despite doing their best for their students. His case can also show us a path for the relief of negative emotions. We suggest that coaching can be used as a strategy to relieve current and future teachers of their anxiety in programs for teacher training and in-service training.