Source:Ihya Ulum ad-Din
You should structure your time, arrange your regular devotions, and assign each function a set period of time during which it is given first priority but which it does not overstep. For if you abandon yourself to neglect and purposelessness, as the cattle do, and just do anything that may occur to you at any time it happens to occur to you, most of your time will be wasted. Your time is your life, and your life is your capital; it is the basis of your transactions [with God], and the means to attain to everlasting felicity, in the proximity of God the Exalted. Each of your breaths is a priceless jewel, and when it passes away it never returns.
(Imam al-Ghazali)