In one of the songs I extended I was struggling over three lines that have a triple internal rhyme - couldn't figure it out. I really didn't think I'd be able to jog today, but after struggling for an hour I decided to try. And naturally the three lines came to me two blocks into the jog and then I had to remember them for three miles, which I thankfully did. The first two-thirds of the jog weren't crazy difficult, but the final third sure was.