Proverbs 27:1: Boast not thyself of tomorrow; for thou knowest not what a day may bring forth.
Because life is a vapor, no creation should brag not only about the next second of their lives, but tomorrow. We don't know what today holds, let alone tomorrow. The gospel group The Winans, had a popular song in the 80's called, "Tomorrow." In the song, the person was sure that the plans that they made to give their lives to Christ "tomorrow" The song echoed, "tomorrow, very well might be too late!" There is a sense of arrogance when we make assumptions like we can guarantee that things will happen tomorrow.
The book of James, 4:15-16 reminds us, 15 For that ye ought to say, If the Lord will, we shall live, and do this, or that. 16But now ye rejoice in your boastings: all such rejoicing is evil. Since we cannot add one hair to our head or make it black or grey, we should humble ourselves and not count our chickens before they hatch!
In closing, no one knows tomorrow or the future, but our Creator. It behooves us to humble ourselves and yield to the One who knows more about our tomorrow than we think we know about today!