It was the hardest work I've ever done in my life (and I've run marathons), but it wasn't that bad. For me, pushing didn't last very long (25 min). It was a bit of a trial b/c I expected to feel relief when pushing, but it hurt just as much (or more) than the last 7 hours or so, which had been very painful. Also, I never had a pushing urge; in fact, I'd been "waiting" at 9++ cm for over 7 hours for that urge that just never came. So I had to push without an urge, which was fine, b/c you just do what you do when pooping, except more. However, I do have to say that I simply loathed and hated the pushing part and the feeling of pushing. It was very, very painful for me, plus it just felt . . . awful!
Needless to say, I'm hoping it's easier/better next time, but not expecting it! Despite how hard it was for me, I still want another babe and am prepared for another vaginal birth.
You can do it! And you're more likely to have an easier, positive pushing experience than the tough one I had. But even if you do, just remember you can do it, and you're approaching the finish line once you start pushing. Although I do remember thinking "Ok, that hurts and stings, this must be crowning. Ok, well then THIS must be crowning" and not having the doctor say she was crowning until several pushes later!
FWIW, I was not flat on my back - I was semi-upright in a bed. It didn't feel any different than the last 7 hrs I spent on the toilet, though, so I don't think it was any harder b/c I was in that position.
I second pushing when you feel the urge to push, but there's always a chance you may never have an urge. Even when I was pushing, there was no urge - I was just "choosing" to push when I felt a contraction. Bottom line, everyone has a different experience. Make sure you have a doula or someone there to remind you that you don't have to push for 10 full seconds or any of that garbage. I had a doctor yelling "push push push push push!" at me, but I ignored it (thanks to my doula reminding me) and just pushed maybe 3-7 sec/contraction, whatever felt right.
I hope you have one of the "easy" "I liked pushing" experiences!
dd 10 mos