Passage
beloved, concerning all things I desire thee to prosper, and to be in health, even as thy soul doth prosper,
beloved, concerning all things I desire thee to prosper, and to be in health, even as thy soul doth prosper,
3 John 1:1 The Elder to Gaius the beloved, whom I love in truth!
3 John 1:2 beloved, concerning all things I desire thee to prosper, and to be in health, even as thy soul doth prosper,
3 John 1:3 for I rejoiced exceedingly, brethren coming and testifying of the truth in thee, even as thou in truth dost walk;
3 John 1:4 greater than these things I have no joy, that I may hear of my children in truth walking.
The verse centers on "all things", "beloved", "concerning", "desire", "thee", "prosper", "health", and "even". It is saying that the verse draws attention to "all things" and "beloved", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 1's "The Elder to Gaius the beloved whom..." into verse 3's "for I rejoiced exceedingly brethren coming and...", so "all things" and "beloved" belong inside that flow. In 3 John context, the local focus is Christ, faith, and discipleship.
A plain takeaway is to answer the verse's own emphasis on "all things" and "beloved" with trust shaped by these words, not by a vague optimism outside the passage.