(Pro 27:1 KJV) Boast not thyself of tomorrow; for thou knowest not what a day may bring forth.
The basic meaning of “boast” (1984b) is to praise or speak well about. It is another one of those words that is not negative in itself but either builds up or destroys depending on how it is used. Here it is used in a negative way. What is the problem?
The target is “tomorrow” (4279). We are being warned not to praise tomorrow. Obviously the problem here is that we often look at what we have done and think it is so wonderful that we can take it to the bank. We make assumptions about the wonderful work we have done. We make assumptions about what God is going to do. That is why the translators chose “boast” in this spot.
So? Prepare. Work. Contribute. Do the best you can but allow God to produce the outcome. Don’t get into the trap of tooting your own horn.