I would definitely agree that one's mindset plays a HUGE role in the outcome of your birthing experience (whether natural or C-sec) I gave birth to a 4.33 kg boy (58cm long!) naturally, without any pains meds, on 29/08/2011. It never occured to me that i couldn't and my midwife certainly never made me feel like it would be an issue having a big baby. This is my first child. I did tear but have already healed up completely (4 weeks later) and things are back to normal
Personally I was really scared of ending up with a c-sec and had to do quite a bit of mental preparation during my pregnancy for the fact that unplanned things happen and it wouldn't be the end of the world if my birth ended that way. Very happy it didn't though as I feel the process we went through definitely helped me bond with him better.
Julz, I grew up hearing about my mom's natural birthing experiences (I was a 4.5kg baby and she is a very small woman) and I think that played a large role in my feelings towards childbirth. I've also always believed that people underestimate the power the mind has in affecting our physical bodies.