Here's a couple of bits from the teachers' background notes that I wrote. I'm talking to myself, really...
"Far, far, far too easy for us to be like the Pharisees. We’re good Christian people who know the Bible inside out and come to church every week. We teach Sunday School. We pray and give. We don’t get drunk and sleep around. We’re not even like those Christians over there with their dodgy theology… and so we can forget how much we need God, and that we depend on Jesus for our righteousness.
On the other hand, sometimes we beat ourselves up about our failures. We know what we should be like, and we’re not. We do the same things again and again; sometimes we give up trying to change, because it’s too hard. When we feel like that we need to do what the tax collector did—run to God for mercy and help."