At Business Week, some thoughts on how to motivate people in their twenties:
Throw them into the deep end on their first day. Excellent managers of younger people give them decision-making authority on at least one mission immediately. One very successful Silicon Valley founder is reported to make everyone in his company "CEO" of something. That's the right idea. If they don't know how to do it, tell them to figure it out. The corollary here is that you can't tolerate learned helplessness. Even very talented younger employees; maybe especially the ones who have the peculiar disadvantages of hailing from privilege;may be tempted to ask you questions they can answer themselves. Make them sort it out for themselves. If you don't, they won't improve. And if letting them solve it on their own feels like too big a risk for you, reconsider assigning the project in the first place. There's always another mission that can be a better fit. As the necessary last step, once they have completed the objective, give clear feedback immediately. Post-mortems are critical accelerators of their learning process.