What does 3 John 1:2 mean?

Three times, John uses the theme of "goodness" or "wellness." First is general encouragement; the same phrase which starts this verse was used to introduce Gaius in 3 John 1:1. Second, John prays a general blessing. Then, he appeals for the health of Gaius. We don't know for sure that Gaius had specific health concerns which would require prayer. One possibility is that Gaius was elderly. The apostle John was quite old by the time he wrote this letter, and Gaius might have been of a similar age. John seems to have known him for some time, and speaks of his church members as children (3 John 1:4). Third, John spoke specifically about Gaius's spiritual maturity. John loved him (3 John 1:1), spoke well of those he led in his church (3 John 1:3–4), and commended his work (3 John 1:5–8).