God is the creator of time. He created the sun and the moon so there would be day and night. The Bible also mentions months and years. Each day is 24 hours long. Assuming that you sleep 8 hours every night, that leaves 16 hours for you to make a difference with.
This gift of today (and every day) from God is something that we can’t return to the store to get what we really want, or regift it to someone else. It is ours alone, and it is our choice as to what to do with it. So now that we realize that this day is a gift from God, what will you do with it? Will you spend the day helping others? Will you spend the day working? Instead of wasting the day doing nothing, you could help spread the Gospel. Or you could spend quality time with your family. The choice is yours.
Only God Himself determines how many days we will live. Someday, your days on Earth will be over and God will come to call you home. When that happens, will you have made the most of the days He has given you? When you see God, what will you tell Him about how you spent the days that He gave you