I see there’s a meme going around attributing this to G. K. Chesterton:
Jesus promised his disciples three things–that they would be completely fearless, absurdly happy, and in constant trouble.
The thought might be Chesterton-esque, but it’s not by Chesterton (and the phrasing doesn’t sound like him either). Thanks to the power of the Interwebz, I was able to find the actual source in about two minutes. It’s from William Barclay’s commentary of the Gospel of St. Luke, which I found on Google Books. Barclay wrote the quotation as given above and goes on to say in the very next sentence:
G. K. Chesterton, whose principles constantly got him in trouble, once said, ‘I like getting into hot water. It keeps you clean!’
So someone (I know not whom) pulled Chesterton’s name from the second sentence and incorrectly attached it to the line from Barclay.