Answer: Too much energy is left after the workout session.
Step-by-step explanation:
Cardiovascular workout is not easy as there is almost no energy left at the end of the exercise. But if the intensity of the exercise in not more then too much energy is left at the end of the exercise.
Michelle knows that his workout is not upto the mark as he feels energetic even after his work out session which is normally not possible.
Hence, he should increase the time or intensity of the session for improving the results.