The Last of the Prophets, upon him be peace, was indeed endowed with exceptional physical and intellectual powers in order to assist him in the most onerous mission ever undertaken. But his nightly vigils in tahajjud prayer and recitation of the Quran, his daily exertion in worship and labour, in unending Jihad, in bearing the problems of others, and all of this continuously for a full quarter century, increasing all the while and never subsiding, in addition to an amazingly light ration of food and drink - all of these factors contributed to wearing down his sturdy body and its decline in health.
In an authentic hadith it is related that whenever the Prophet, upon him be peace, had a physical complaint, he would recite over himself the last two chapters of the Quran and sufflate. Imam Zuhri, one of the narrators of this hadith, was asked how the sufflation was performed. He answered that the Prophet, upon him be peace, would blow into his hands and then rub his face with them.
"Remembrance & Prayer" - Muhammad Al-Ghazali, pp. 116, 117