One of my prayer books says that wandering thoughts during prayer are not always a bad thing. Rather, God wants to help us with the problems in our lives and may be helping us try to find solutions to them. I would like to think that was the case rather than just a lack of mental discipline on my part.
Today's homily started with the story of the three blind men trying to describe an elephant to each other based on what part of the elephant they happened to be touching. To each of them, the elephant was something different and they could not understand how the others could be so wrong. God is a great deal larger than an elephant and we all have a rather limited perception of His vastness, yet we are determined to make everyone else see God the way that we see Him, and only in that way. Now, I do believe that there are some fundamental Truths to God (e.g. the Trinity); however, I do worry when people try to force others to only see God their way. Perhaps they're only holding onto the elephant's tail.