I think the next thing we need to remember is to think long-term. Youth ministry is a marathon, not a sprint. And results look different in youth ministry than they do in adult ministry.
Adults are much more adept at making outward changes than teens are. Inner changes are just as difficult for both groups. Teens are also good at "faking it."
The real test of a good youth pastor is if his or her teens are still serving God 10 - 15 years down the road. If my former students have solid marriages (and good kids) and solid relationships, if they are good employers or employees, and if they are still serving God and pursuing His plan for their lives years down the road, then I can consider myself a successful youth pastor.
If the timeline of their lives could be represented by a line (a continuum), then my influence in their lives as a youth pastor would basically be a dot. As a youth pastor, I have to concern myself with the line rather than with the dot. And that affects the decisions I make, the things I preach and the example I set before them.