work that is done for enjoyment, rather than to make money
—Mrs. White could charge people to visit her flower garden, but she lets them come for free. To her, raising flowers is a labor of love.

Paul opens his letter to the church in Thessalonica with a statement of gratitude:

We thank God always for all of you as we mention you constantly in our prayers, because we recall in the presence of our God and Father your work of faith and labor of love [labour of love] and endurance of hope in our Lord Jesus Christ. (1 Thessalonians 1:2,3)

While Paul uses labor of love to mean “work done because of love for God and for others,” in its modern usage it is often used for a person’s love for the work itself.