indeed, time is life and it is the most important blessings of Allah upon us.  Whatever is gone will neither come back nor substituted.  Therefore, our great faith urged us to seize the moment and try to invest it in what is beneficial and useful for us in this life and in the hereafter.  The Prophet peace be upon Him said: ""Take advantage of five matters before five other matters: your youth, before you become old; and your health, before you fall sick; and your richness, before you become poor; and your free time before you become busy; and your life, before your death."  Nasa'i: Sunan AlKubra: 10: 400

There is old saying that: the prudent person has three hours: one hour he is talking to his Lord, one hour he is accounting for himself and one hour for his affairs of eating and drinking.  Ahmed Shauky, the Poet, said:

The heart bump of the person says to him: that life is about minutes and seconds

 The believer should spend his life on pursuing to fix his life, perfecting his work and obeying his Creator till he obtains happiness in this life and in the hereafter.  Abi bakrah said: a man said: O Messenger of Allah, who is the best person? He said: he who lives long life and does good deeds".  Tirmizy: 2252

The best role model for us in utilizing our time is our master Muhammad peace be upon him who would gave every time its due share, who would conduct his duties towards his Lord, his family, his community as well as his companions.  He never experienced laziness nor tiredness.  In twenty-three years he conveyed a revelation, he built human civilization that was never seen before by the account of far and near. 

Islam is calling us to seize our time for what is beneficial for us in this life and in the hereafter; that is why there is a time for each act.  There is a time for worshipping, the believer is responsible for any work that he carries out, any hour that he spends, every word that he utters.  If the person busies himself with that which does not concern him, and squanders his time for that which does not please Allah; and he messes with other peoples' business, then he had committed an idle talk and would be negligent of his duties, and carrying out his responsibilities; and would expose him to questioning in the Day of Judgment about wasting his life on something was futile. Allah sworn by time that he is in great loss if he does not fill with acts of obedience to Him Almighty.  God said: "By (the Token of) Time (through the ages), Verily Man is in loss, Except such as have Faith, and do righteous deeds, and (join together) in the mutual teaching of Truth, and of Patience and Constancy.." chapter: 103

Because of the importance of time, God sworn by different times such as: Dawn, Morning, Morning light and by night.  The reason is that the incumbent duty upon the person towards his time is to take care of it, to try to get most of it in your all affairs.  The Muslim spends his time either practicing devotional practices, or a duty that he takes care of or raising his kids and protecting his family, or teaching them a beneficial knowledge or doing good, or visiting a sick person or connecting the tie of relatives or visiting a friend.  This is in line with the good peoples' character who are praised by Allah Almighty, by saying:  "These (three) were ever quick in emulation in good works; they used to call on Us with love and reverence, and humble themselves before Us." 21: 90   

About the student should spend his time in studying and obtaining knowledge and to prepare for the exams; for that would help him reach his dreams and would realize his goals and objectives.

About the worker or employee, his innovation and excellence can be achieved by seizing the working hours and spending in completing that which was required of him and performing that which was delegated to him of different tasks. Therefore, he would be of those who carried out the trust, fulfilled their covenant and conducted goodness for himself, family and community. 

O servants of Allah, be vigilant with your taking advantage of your time, and invest it in your world affairs and in the hereafter.  Make sure to stay away from anything that does not concern you in line with the Prophet's instructions when said:  "To beautify your Islam leave alone that which does not concern you".  Tirmizy:  2317