Jeff Atwood of Coding Horror fame recently posted an article titled Quantity Always Trumps Quality, the main point of which is that endless designing and theorizing is a waste of time, and that that time could be better spent building something. The idea is that the time you spend failing early on is time spent learning to do whatever it is you're attempting to do the right way. That's a benefit you don't get by spending time designing the wrong thing. While this idea isn't new or original it is still excellent advice, and Jeff shows how it applies to a wide range of disciplines, from making clay pots to software development and blog writing.
One reason that I like this advice so much is that it teaches us not to be afraid of making mistakes. Not only that, we can learn to embrace our mistakes because that is, after all, how we learn. I've often felt that if something is stagnant (a software project, your company's sales, a personal relationship), doing any random thing to get out of stagnation can be better than doing nothing at all. Once you make a random change you can analyze the results and see what you need to correct. If you go into the change with the mindset that it's only purpose is to teach you what you really should have done, it makes it a lot easier to bear when you make a mistake.