I think that the coach should tell him to 1st get more sleep because once a person runs a lot, a lot of their energy is being used, if that person does not get the proper sleep (at least 8 hrs) and does not have enough food they will begin to feel tired. this could also have to do with dehydration, One also needs to be drinking a lot more water while exercising. While on the subject of health, An apple after or before each meal can give a person a lot of energy also an orange before a workout can also give energy . Hope this helps!