My first reaction to hearing that is, "Of course I can wait. You just sit, and wait." But is that really true? True, that is one way to wait, and that's probably the reason for many people's frustration. But there are other ways to wait too.
Every once in a while my mother comes to visit. One way I can wait is to sit. When's mom going to get here? But we usually wait a little differently. "Waiting" was cleaning, straightening, getting extra groceries, doing all the things to prepare for her arrival.
Maybe one of the reasons we get frustrated with God is because we don't know how to wait. What if instead of just sitting "waiting" on God we decided to actively wait, pray, read our Bibles, serve, love others, do all the things that help us understand God better and in turn allow us to recognize Him when He shows up?
Imagine how different our churches, our society would be if we knew how to really wait on God...?