In 2 Corinthians I found three acts of service that have explicit results listed which benefit both people and God:
1:11 And you are helping us by praying for us. Then many people will give thanks because God has graciously answered so many prayers for our safety.
Service: Praying for those taking the gospel.
Result #1: God answers those prayers.
Result #2: God will be thanked, especially by those who prayed and those who receive the gospel.
4:13-15 But we continue to preach …And as God’s grace reaches more and more people, there will be great thanksgiving, and God will receive more and more glory.
Service: Going to take God’s grace to people.
Result #1: People will overflow with thanksgiving to God.
Result #2: God will be greatly glorified.
9:11b-13 And when we take your gifts to those who need them, they will thank God. So two good things will result from this ministry of giving—the needs of the believers in Jerusalem* will be met, and they will joyfully express their thanks to God. As a result of your ministry, they will give glory to God. For your generosity to them and to all believers will prove that you are obedient to the Good News of Christ.
Service: Giving to God’s people.
Result #1: Their needs of our brothers & sisters will be met.
Result #2: The recipients will thank and glorify God.
Result #3: Our obedience to God will be evident.
After I did this study, I did a double take when I realized that the three acts of service happened to be the well-known “Pray, Give, Go” formula—only in a different order. It’s kinda neat when things like this come out inductively rather than setting out first to “prove” something!