nevertheless at Your word I will let down the net.”
When we cease trying to do what we cannot do then the Lord will begin to do what only He can do anyway. “And when they had done [what Jesus said to do] they caught a great number of fish, and their net was breaking” (Luke 5:6). Peter, James, and John can try as they might and do their best, but without the word of the Lord it is in vain. They might have saved themselves a lot of effort had they sought the word of the Lord to begin with.
Which would you rather have: a whole night of wasted effort on your own, or five minutes of abundance with the Lord? Yes we should work, but first we must wait. And if we will wait for the Lord then we will have Infinite Supply for the work at hand.