Time is the Most Precious Commodity
The Midrash (Bereishis Rabba 58:3) states, "Reb Akiva was teaching Torah and saw that his students were falling asleep. To awaken them, he asked, "Why did Esther rule over 127 countries? It's because her ancestor Sarah lived 127 years."
The Chidushei HaRim zt'l explains that this awakened his students because it taught them to utilize each minute of life to its fullest. If Sarah, chas veshalom, had wasted a year of her life, her descendent, Esther, wouldn't have ruled over the 127 countries.
The Chidushei HaRim elaborates, "Each week of Sarah's life granted Esther a city. Each hour granted Esther a town worth thousands. This means that when one oversleeps, he's losing thousands of rubles!" This encouraged Reb Akiva's students to stay awake, for they became aware of the value of time, and that there is no greater loss than lost time.
About Avraham, it states (24:1), בא זקן ואברהם בימים, "Avraham was old, he came with his days..." This also indicates that he utilized every moment of his life for avodas Hashem. He came with all his days.
In a letter, the Yismach Moshe zt'l, encouraged his son to be cautious not to waste time. He writes, "'ה למען, For Hashem's sake, distance yourself from batalah, idleness, as distant as a shot arrow... If a person threw a package of money into the sea, people would consider him insane. Even more insane is someone who throws a drop of his time away and engages in idle talk."
Similarly, the Yaaras Dvash (2:10) writes, "No, my sons. It's not good that we waste precious time with foolish things that have no value... They waste their time at night, and when the sun rises, they roll over from side to side and miss the last zeman tefillah. One sin leads on to the next."
In another location, the Yaaras Dvash (1:4) writes, "My brothers, please, awaken from your sleep. Don't waste precious time with the foolishness of the world, such as idle talk, discussing wars (who will win and who will lose), hunting, or other forms of emptiness. These are deeds fitting for princes, but why should you waste precious time on them? It's very foolish to exchange the real world for a world of falsehood. How can one waste time!? If one is destined to die on a certain day, and someone offers him millions if he agrees to die one day earlier, I know that he won't accept the money, regardless of its large quantity. So, if a day of life is so precious to you, how do you waste it with idleness? He is the שוטה, fool, stated in Chazal (Chagigah 4), who loses everything that's given to him. Because time is a precious gift from Hashem; with time one can know Hashem, attain perfection, and correct his deeds. With time, one can attain the eternal world because all perfection is attained specifically in this world."
The Gemara (Yoma 86:) teaches, תשובה גדולה אדם של ימיו שמארכת, "Teshuvah is great, for it lengthens the lifespan of man." The Tzlach explains that teshuvah doesn't add more years to a person's life; teshuvah resurrects and fixes all the dead days – days that weren't called life. Before one does teshuvah he has many dead days, which aren't counted as part of his life. When one does teshuvah out of love (מאהבה תשובה) his sins become mitzvos, and his past days are resurrected and are now counted as part of his life. This is how teshuvah "lengthens the lifespan of man."
A Parable on the Value of Time
The following mashal is told: Someone entered a cemetery and read the headstones, "Here lies Reb Shimon ben Dovid. He lived for two years." Most matzeivos read that the niftar lived one or two years. The oldest among them was the rav of the town. His headstone read, "Here lies the rav of our city... He was ten years old when he died." "What's this all about?" he wondered. "Was there an epidemic in the city, and everyone died young? And how could it be that the rav of the city was only ten years old?" He went into town and asked the wise men for an explanation. They told him, "In this city, we don't write how old a person was when he died; we write the number of years he lived. Only the hours utilized for Torah, tefillah, and mitzvos are considered time lived. We add up the hours he spent living, and that's what we write on the headstone. Sadly, sometimes a long life adds up to just about a year."
Chazal (Brachos 18:) say, מתים קרואים בחייהם רשעים, 'Resha'im are called dead, even in their lifetime.' True, they are living, but they are as good as dead because they aren't using their time productively for Torah and mitzvos. Regarding learning and keeping the Torah, it states (Mishlei 9:11), ימיך ירבו בי כי, 'With me, you will live long.' Ultimately, only time used in service of Hashem is called living.
It states (Tehillim 90), חסדך בבקר שבענו, kindly grant us the ability to do teshuvah, ונשמחה ונרננה, and then we will rejoice, ימינו בכל for we will get back all our days.
