Are you actually comfortable and relaxed when you are doing the act? Or are you all wrapped up thinking about it? Are you generally a stressed and anxious person?
My advice would be for your next punt don't even worry about finishing, just have a nice time and enjoy the journey and let the destination take care of itself. It might take a few punts to really get into that mindset, but worrying about finishing can, ironically, impede you from finishing.