The story of Jesus as a twelve year old visiting Jerusalem on the Feast Days with his parents and being left behind has been on my mind lately. He said at that time, “Don’t you know I must be about my Father’s business?” What was Jesus, as a 12 year old, able to do to be about his Father's business?"
Well, where did his parents find him? -- In the temple. Doing what? -- Asking questions of the scribes and priest. Probably listening to their debates and teachings. In short, he was studying the Word of God. He was building up a bank of knowledge to be used later when he would be able to do something with it. To me, that's the lesson of the story.
When our young people decide it is time to be about their Father's business, and that's what they are saying by being baptized, what should they be doing? Realistically, most 12-15 year olds can't go on missionary journeys to Africa, South America or Asia. They won't even be very effective trying to teach in their neighborhoods because most adults aren't going to listen to a teenager tell them how they should live their lives.
So, what can they do? Exactly what Jesus did: study. Learn the Word of God. They should try to get as comfortable with it as Jesus who, even though unable to carry around a Bible, quoted it liberally and was confident enough of his command of scripture to make arguments based on the tense of a verb. Our young people should be building up a bank of knowledge now so that later, when all of the various opportunities to use it begin to arise, they will be ready. If a young person isn’t busy “about his Father’s business,” then maybe he has no business trying to make a lifetime commitment to it yet. Jesus didn't waste his youth "hanging out." He got ready for his adulthood.
But as for you, continue in what you have learned and have firmly believed, knowing from whom you learned it and how from childhood you have been acquainted with the sacred writings, which are able to make you wise for salvation through faith in Christ Jesus. (2 Timothy 3:14-15)