none of these things move me; nor do I count my life dear to myself, so
that I may finish my race with joy, and the ministry which I received
from the Lord Jesus, to testify to the gospel of the grace of God."
Acts 20:24 (NKJV)
In a school, you will take classes about different subjects and for each class you will receive a grade when that class is done. Sometimes a person does an excellent job with the subject they are learning about in class and they receive a very good grade, and sometimes people do not do so well and they receive a poor grade. The main goal is to pass the class, and while everyone wants a good grade, some people are just happy to finish the class and pass.
In Acts 20:24, Paul talked about finishing his course, with joy. In 2 Timothy 4:7, Paul said he had fought the good fight, finished his race, and kept the faith. Paul did not just say that he finished the course, but he finished with joy! Paul did not say he just fought and had faith, but he said he fought the good fight and that he had kept the faith. Paul's goal was not just to finish and be done with what God called him to do, Paul's goal was to finish in the best way that he could!
In the parable of the talents in Matthew 25, the faithful servants were commended for doing a good job with the words of "Well done" and not just, "Well, at least you are done". In the same way, Paul did not want to just barely cross the finish line of the race that God gave him to run, Paul wanted to fulfill the will of God as best he could. Paul did not want to just pass the class and make it through, Paul wanted to get the best "grade" he could for doing the will of God. We need to have the same attitude that Paul did and strive to do the best we can in the will of God.