I had a posterior labour with my first baby. I laboured for 33 hours - contractions began with a bang 2 minutes apart and remained that and closer for the entirety of the labour. It was so exhausting and the pain in my back was really tough.
For me though I was really well supported. I wasn't scared as I understood and knew why things were so intense. In the end DD was a brow presentation. It was undoubtedly a painful labour. But for me it was manageable and had a purpose.
I had a perforated appendix when I was younger which was intensely painful it was frightening and scary but for me birth wasn't as I trusted in the process, I felt safe and supported and I knew and believed in the end I would get that little person out!

It is wonderful to hear everyones different stories and feelings. I have a girlfriend who literally feels no pain in labour. None. Her second birth she didn't even know she was contracting.
She had a visit at her obs and he had asked to have a peek at her cervix as she was due - she was 8 cms. Her son was born half an hour later with absolutely no sensation of labour. Her twins were born vaginally the same way. Although with them she had the burning sensation of the head crowning but that was it....

We all experience labour differently. I believe feeling safe and supported eases the discomfort as does being able to move freely about.