"This is the day which the LORD hath made; we will rejoice and be glad in it."
The Lord, who was and is and always will be, has made this day, today.
He made it. He knows what's ahead, he understands what is behind.
He has taken care of everything for you.
"For ye shall not go out with haste, nor go by flight: for the LORD will go before you; and the God of Israel will be your rereward." (Isaiah 52: 12)
"Behold, the eye of the LORD is upon them that fear him, upon them that hope in his mercy;" (Psalms 33: 18)
"And the LORD, he it is that doth go before thee; he will be with thee, he will not fail thee, neither forsake thee: fear not, neither be dismayed." (Deuteronomy 31: 8)
Jesus Christ is the same yesterday, today, and forever.
He is the Creator of all things, and all things are made of Him (Colossians 1:15-17)
He made this day, too.
He made the day, therefore He is greater than the day itself, and thus He is over everything that you may face:
"4Ye are of God, little children, and have overcome them: because greater is he that is in you, than he that is in the world." (1 John 4: 4)
That includes every day, including this day.
Rejoice and be exceeding glad!