Hello. Here's some advice for when you try more single player replays.
First off, try not to be symmetrical. That means that you don't move a part of your body that is on both sides. For example, a symmetric replay would include you raising both shoulders at the same time, or contraction your knees at the same time. Try more asymmetrical things, where everything is different.
Also, try to be more relaxed and limp. That means start by relaxing all your joints then work from there. Every once in awhile press c again to relax again.
Good luck and keep practicing : )