“Gotta keep the muscle guessing, you don’t want your body getting used to the routine.”
I used to say that all the time, and now I know I was dead wrong. You actually DO want your muscles and body to get used to your routine. In fact, you want to become as used to the workout as you possibly can!
Supposedly, if your body and mind get used to working out in a certain way then your progress will stop. The truth is, you’re never more ready to make progress and massive gains as once you get used to doing something.