I've been trying to get to the point where i can do a set of 100 situps as a "proving my self will" kind of thing..but I'm not sure, should i tuck my chin into my chest as im doing this, or should i try to keep it as if i was staring at the ceiling originally and my back just happened to move? I've always been told the latter was best for your neck and to even put a fist under your chin to make sure you don't move your neck..halp?
dont tuck in your chin, keep your neck straight so you can breath BETTER and take deep cock