Endurance: towards the legend. Once you have opened up the last 'Gig' with the Dog as you are leveling him up, keep doing it. Choose it every time and complete it 10 times in a row without backing out, failing, switching off your console etc etc. It sounds worse than it is, just hope that you get 60 songs which aren't impossible to pass (there were a few I could never manage which had odd bits which went to miss straight away). However, I never encountered these while playing as the Dog. This is simply perseverance, can be done on the way to the Legend Dog achievement.