Islam considers health to be one of the greatest blessings to have been given to human beings by God. Indeed, it is considered the greatest blessing after faith itself.
The Prophet 
said: "There are two blessings which many people do not appreciate: health and leisure".
He also said:
"No blessing other than faith is better than well-being".
As an aspect of grace, man should express gratitude to God for it, and it should be properly looked after. Good health is something for which we are accountable to God.
The Prophet said:
"The first thing every servant of God will have to account for on the Day of Judgment is that he will be asked by God: Have I not given you a healthy constitution and have I not quenched your thirst with cold water?"
The Prophet also said:
"No one will be allowed to move from his position on the Day of Judgment until he has been asked how he spent his life; how he used his knowledge; how he earned and spent his money; and in what pursuits he used his health".
It is part of the duty of every Muslim, therefore, to safeguard this blessing and not to allow any change to overcome it through ill usage. Otherwise, he will be severely punished, according to God's immutable laws.
The Quran states:
"Anyone who tampers with God's grace after it has been bestowed on him will find God to be stern in punishment".
[surah al-Baqarah; 2:211]
"God would not alter any grace He has bestowed on a folk unless they alter what they themselves have".
[surah 8:53]
Taking good care of one's health and taking every measure to maintain and enhance it. On the basis of this principle, every Muslim should make sure of doing whatever doctors confirm to be conducive to the preservation of good health. Moreover, the Quran and the Sunnah contain teachings that shows every Muslim how to protect his health generally and how to take care of each of his organs.
An important means of health protection and promotion is to give to each part of our bodies its due.
The Prophet said:
"Your eyes have a claim against you".
One must not overburden oneself: "Bear only what you can cope with".
This should be accompanied by increasing physical fitness through exercise and sport. The Prophet said:
" A physically able believer is better than a weak believer"'.
He also said:
"Your body has a right on you", and "Be keen to do what is of benefit to you".
In return for all these ways and means of protecting and promoting our health that have been mentioned above, we are strongly warned against making any attempt to alter this aspect of God's grace. If we do, we will pay a very heavy price. This is clearly highlighted in the hadith "When gross immoral conduct becomes widespread in any community to the extent that they unashamedly publicize it, plague and other diseases unknown in their past generations will spread quickly among them". God has categorically forbidden all foul and sinful practices, regardless of their nature.
He says in the Qur'an:
"You shall not commit foul sins, whether openly or in secret."
[surah 6: 151]
Another Qur'anic directive states:
"Say: My Lord has forbidden all atrocities, whether overt or disguised, and harm".
[7:33]
said: "There are two blessings which many people do not appreciate: health and leisure".