The reason to turn brick walls into motivating forces is that if we don't, they become excuses as to why we can't accomplish things. We can all do much more than we think, once we decide to do it.
It's very hard to find meaning in one's life. It's much easier to find "meaning in one's actions"—so look for someone who could use your help, and help them in any way you can. If your actions all have meaning, I suspect your life will begin to as well.
The one thing I wish we'd all think about right now—and forgive me for being mundane—is this: If you have kids, review your life insurance, because most people don't carry enough. More broadly, we should think about the fact that time is a zero-sum game. Things we spend time on inherently take time away from other things. So constantly ask, Is this the best and highest use of my time?
Randy Pausch passed away in August 2008.