Melatonin is created in the pineal gland, hope this helps!
Answer:
After he has adjusted to his exercise routine he should increase the intensity of the workout. Ex. add weight/ increase reps. This will help get his heart rate higher.
Explanation:
working in the cardio will help to tone your abs and burn excess fat, and the respiratory system, with it being in good health from the exercise, your oxygen intake and the release of carbon monoxide will definitely increase and become steadier..