The book 'The Toyota Way' and a book by Shigeo Shingo (helped develop the TPS) - 'Kaizen and the art of creative thinking' changed the way I think about completing tasks or achieving goals. While they are more based on manufacturing the lessons hold up well for any discipline. Basically, once you realise that everything has room for improvement (nothing is ever perfect!) and it's consistent small changes/improvements that make things better, it takes the pressure off trying to do things exactly right the first time. Treat tasks/projects as experiments, come up with a few hypothesis, pick one, do it and asses how it went and what can be improved or throw it away. At least you're getting stuff done and you might just end up with something better than you would by trying to force a perfect job/product from start to finish.