The horse is made ready for the day of battle, but victory rests with the LORD. (Proverbs 21.31, NIV)
There are two extremes, none of which you should be in. One person says God is in control and locks his hands between his thighs. He is lazy and irresponsible, because he thinks all responsibility is God’s. He spends his time on some religious activities thinking they will cover up for his irresponsibility. This is a bad extreme.
The other person thinks her destiny is in her own hands. She is her own god and everything depends on her. She believes in pragmatism and does not really believe in what the people of faith say. Her faith is in working hard, making money, networking and all that must be done for success or victory. The ball is in her court. She wakes up and quickly gets to work without praying. She knows that work is how she will win. This sister is also in error.

Proverbs 21:31 says that the Horses and Chariots are prepared for battle but victory comes from God. There is indeed the role of man in actively preparing for battle by every human means necessary. As part of this preparation or throughout this preparation, however, the man is urged to know that victory, salvation or deliverance in the day of battle rests with God.
There is indeed a day of battle that we must prepare for. We must know that it will come, sooner or later, in one form or the other. God is not of the school that think we should get to the river before we think of crossing it. He is certainly against us being anxious of tomorrow, but He is all for us planning and preparing for perceived dangers ahead. Battles are not won by sudden bravery in the day of battle . Rather, a serious contribution to triumph is the preparation that precedes the battle. The Bible says in Proverbs 24:10 that, “If you faint in the day of adversity, your strength is small.” The day of adversity is not the time for building strength. We need to have a victory-ready attitude all through our lives by constantly preparing through reading, learning, investing, praying, studying the Word.

We are to continue to build ourselves in the most holy faith (Jude 1:20). We are to be with God and the word of his grace which is able to build us up towards the day of adversity (Act 20:32). God will build us through the process of time and our active devotion to Him and His Word.
And now, brethren, I commend you to God, and to the word of his grace, which is able to build you up, and to give you an inheritance among all them which are sanctified. (Act 20:32, KJV)

God indeed gives victory. Whereas the victory RESTS with Him, it is actively given to us even through our human readiness. The word translated “victory”, “deliverance” or “salvation” in Proverbs 21:31 is “teshuah” which means deliverance usually given by God through human agency. That is, this victory comes by God but through human agencies such as the horses and chariots. God blesses the activity of man and crowns it with victory. Teshuah is God making us prosperous in what we do, and not He blessing our laziness.
Related Podcast: https://open.spotify.com/episode/0Kb0z6J9aHepq7ADQZ1At3?si=BjnZMYGhRaChpA5NHmkdFg&utm_source=copy-link

(Proverbs 21.31, NKJV)