I'm only 19 years old, so I can't speak for many. However, I've found that when I (or my friends) suffer from this "the excitement is gone" bug, I recommend learning how to program web applications. They let you make something big that can instantly be deployed to millions, and some frameworks like Ruby on Rails have a veyr low barrier of entry.

Also, with web applications you get to make websites, and experience the thrill of crazy traffic, ad revenue, and making sure people have a good time.

Web apps is what brought the excitement back to me. Again, I'm 19 so I'll most likely end up finding another vehicle for my excitement in the near future.