I just posted this in the “claustrophobic” thread, specifically about stall doorways and getting my horse to go quietly in and out, but replace “doorway” with “puddle”, and the same thing applies. I’ve done the puddle thing too. It just need to be wide enough (left to right from the horse’s perspective" that he can’t go around it. Ask and let him think, ask again if he deviates backwards or to the side or just disengages his brain, let him alone and thinking if he’s facing the puddle.
"I did that with my OTTB mare when we got the barn built. She would RUN into the stall, and RUN back out. I mean, OTTB, she had a LOT of in and out stall time!
I put a 12’ lead rope on, taught her basic “point and go that way”, and then we did that over and over with the stall. I stood on the outside for both in and out. I asked her once to come out, or go in, and as long as she was facing the right way and actively thinking about it, I ignored her. But if she backed up, or turned her head, I didn’t reprimand her, I just asked again.
It took a few days, of dozens of ins and outs, for her to start walking out reliably, even if it was still in a worried and hurried manner. A few more days and she was totally quiet about it, and it’s never been a problem since.
But the “point and shoot” needs to be solid before you add an obstacle to it, because whatever level of solid training you have for a given thing, expect some degree of training “loss” when you introduce something new."