Life is nothing but an accumulation of many breaths. So every breath is just a precious diamond which cannot be purchased with anything in the world. It is a priceless jewel which has got no substitute in value. So in movements and talks, and in sorrows and happiness, such a priceless breath should not be spent in vain. To destroy it is to court destruction. An intelligent man cannot lose it. When a man gets up at dawn, he should enter into an agreement with himself just as a tradesman contracts with his partner. At that time, he should address his mind thus: O mind, you have been given no other property as precious as life. When it will end, the principal will end and despondency will come in seeking profit in business. Today is a new day.
Allah has given you time, that is, He has delayed your death. He has bestowed upon you innumerable gifts. Think that you are already dead. So don’t waste time. Every breath is a precious jewel. Man has got for each day and night twenty-four treasure houses in twenty-four hours. Fill up these then find them filled up with divine sights in the world next. If they are not filled up with good works, they will be filled up with intense darkness wherefrom a bad stench will come out and envelop them all around. Another treasure house will neither give him happiness nor sorrow. That is an hour in which he slept, or was careless, or was engaged in any lawful work of this world. He will feel grieved for its remaining vacant.
[Taken from al-Ghazali: Meditation and Introspection, The Book of Constructive Virtues, Ihya Ulum-id-din.]