For my DD2 (first labour) my body did it all of it's own accord. I didn't realise what was happening until a few cx had passed (anterior placenta). Completely uncontrollable. Took me 50 mins but it was hard work and I put in a lot of effort.

DD3 it's kinda hard to say. She was crowning without me feeling any pushing, pressure, burning, or coming down (I had cx, but nothing that indicated she was even close). I gently pushed her out, so it was half my body and half me trying to manage it as slowly as I could. Def couldn't stop my body though. No real effort at all, I feel like I cheated at birth... (No idea on placenta, it was fairly low at 20wks and I think posterior because I could feel everything at the front).

You're right, Tasha. Different for every woman and even every birth.