Jacob assembled his sons to give them his blessing before he died. The exact words of the Torah are, "He blessed them on that day" (Genesis 48:20). What is the significance of the fact that he blessed them on that day?
We may translate the verse to read, "He blessed them with that day." Jacob gave them a blessing that they should live their lives on that particular day in which they find themselves, unencumbered by the burdens of the past and without assuming futile worries about those events which are not subject to change at the present.
This is indeed a blessing. If we would only channel our energies toward doing that which can be productive, instead of squandering them in trying to make yesterday better, or worrying about possible eventualities about which we can do nothing now, how much happier we would be!