My son is 22 months old and we've been potty training since he first showed VERY obvious signs at 17 months. Initially we weren't very committed but he's been in pants and not nappies for about 3 weeks now, still with quite a few accidents. But the big thing was his fear of poo.
It didn't matter what we did, he just screamed if you tried to sit him on the loo to poo. I tried just about every approach going and eventually thought, screw it. I'm going to get medieval on your butt.
So two days ago when I could see him going into his poo dance, I sat him on the toilet. He screamed blue murder and did his utmost to get off but I just kept holding him there. When the poo came, you could see his expression went from terror to 'What, was that it?' So the experience of pooing wasn't nearly as terrifying as he imaginged. Next day repeat episode although with less screaming and head butting.
Today - went to the toilet to poo 3 times without a peep. he simply said: Poo and walked to the loo. And afterwards said: chocolate - which is his reward.
So hoorah! Call me a meanie but it worked.