Therefore do not worry about tomorrow, for tomorrow will worry about its own things. Sufficient for the day is its own trouble. —Matthew 6:34 NKJV
The grace that God has given you is for today, not tomorrow. He wants you to live in the present. Some people live in the past by saying things like, "If only I knew this . . ." or "If only I was born in a richer family," etc. Others live in the future, being concerned about things that might happen, questioning, "What if this were to happen . . ." Proponents of mental health say that people who can live in the present are mentally healthy. Jesus knew this during His time, and that’s why He spoke about it in Matthew 6.
The Lord wants us to go to Him and receive from Him daily. The supply that the Lord has given us today is not to be used for tomorrow. When tomorrow comes, the grace will be there—just like how the Israelites received manna every day.