As a teacher of our parish Confirmation class, I can attest that this is a difficult age group. My experience is, unless the child has been brought up in a devout home where the family’s faith is primary and not cultural (and sometimes even then), the child is at high risk to lose interest and fall away in the teen years.
Confirmation class attempts to teach the doctrines of the faith and should provide activities and service opportunities for putting Church teachings into practice. At the same time, we need to teach these lessons in a vibrant way to keep the attention of these youth who are used to a fast-paced, secular culture. It can be difficult for teachers to do this, (Before anyone jumps in to flame teachers, I would suggest that if you think you can do a better job, please step up to the plate.) and consequently some teens will lose interest. Also, even devout teens can rather easily be side-tracked by the strong lure of the temptations of secular society.
I agree with the previous poster that at this point, there’s probably not a sound bite that would reinvigorate a disinterested teen. But in an effort to try, I would emphasize to the teen that in a world where things seem to be constantly changing and often challenging, our faith is a rock, and keeps us on a path to what is right and good. Confirmation is a sacrament where teen receives the strength of the Holy Spirit to live as a Christian. It is exciting (to me, anyway) to think of a teen receiving these graces to help him.
It’s interesting that you phrase the problem in terms of what the sacrament “gets you.” If you are looking for something tangible, well, there isn’t anything tangible that Confirmation gets you. (As an aside, I’ve always been fascinated that Ash Wednesday is so popular, and I think it’s because Ash Wednesday “gets you” ashes. If it was “just” a Mass without anything (other than the Eucharist) being given out, I bet it wouldn’t be any more well-attended than your basic Holy Day of Obligation - which in my experience, they are attended in much fewer attendance numbers than Ash Wednesday. And yes, I know Ash Wed is not a Holy Day of Obligation; I’m just saying.)