I've pretty much conditioned myself over the last 6 months just doing half-ass strectches now and then. I clamp a few times a week and tug on it throughout the day. However, I want to get serious again. Im going to start with some bundled stretches, A-stretches along with my usual ups and downs and cranks. When doing these stretches how hard should i be tugging without injuring anything? A percentage would be appropriate.