The book of 2 Corinthians opens with the words, "Paul, an apostle of Jesus Christ by the will of God. . ."
The words, "by the will of God" are important, because they indicate that Paul was an apostle of Jesus Christ, not by his own doing, but by the will of God. In short this means that Paul didn't appoint himself but instead was named by God to be an apostle.
We are all appointed by God to do something (or perhaps many things). When we do the things that God assigns to us, we experience many benefits. But many Christians grapple with knowing the will of God. The great news is, God makes His will clear in every book of the Bible.
The book, By the Will of God: Christian Devotional Readings from 2 Corinthians, explores the will of God as revealed through the book of 2 Corinthians, and the following benefits you'll experience as a result practicing them:

You may feel inadequate to do what God calls you to do, but when you're obedient to His will, He'll equip you to do the work, and you'll succeed. Because of that, you can move forward with confidence

Doing the will of God blesses others that are impacted by what we do.

Doing the will of God advances God's Kingdom. This is the ultimate purpose in doing the will of God.