Okay, walls aren't all that fun,
but the biggest worry I have at the track is rollover, because that could result in serious injury. At least walls and armco will stop you before your car has a chance to catch an edge and roll over.
Fortunately, both rollovers and collisions with walls are very rare events at the track. And you just need to do what Tiger Woods does on the golf course...he focuses on where he wants the ball to go, not where he doesn't want it to go. So, just focus on where you want the car to go, not where you don't want it to go. If you look at something (a wall for instance), you will naturally steer towards it.