Do not boast about tomorrow, for you do not know what a day may bring forth (Proverbs 27:1).
As children of the Heavenly Father we are to prepare for the future, but not brag or be overconfident about what we may or may not do. Boasting is pride. We are, however, to show humility toward and trust in God. It is wise to work and study hard, to prepare, to provide for the future but in complete faith and trust in the Lord who controls the future.