Even though I now recognize it, I am still afflicted by it: I have this notion that creative works spring fully fledged from the mind of their creator. So why do I care? Because it taps into my inability to be creative. That is, I expect that if I wish to create something new that I will need to map it out to the nth degree before proceeding.
That notion is, of course, poppycock. I have seen it refuted in writing music (when I worked in theater), and in completing crafts (my wife). I have experienced it myself while doing some computer programming, and even when cooking. None of us is Mozart, who in the movie Amadeus says, "It's all up here, I just need to write it down." Most creation is an iterative process: a framework, some details, flesh it out here or there... Give yourself space to experiment. Do not be afraid to throw it away and start over. Add things to see what happens, and if they work, great; if not, try something else. Then cut, edit, cut, edit, cut, edit until it is right. 1% inspiration, 99% perspiration.
Now this may seem obvious. It may feel unnecessary to be stated. Duh. But still, my default mode of thinking is that I have to be perfect the first time, and that leads to apathy (why even start?) and anxiety. I know that I am not the most creative person(1), but working past this mindset helps me to get things done: writing a test plan, cooking a meal, or editing a blog.
(1) I am actually not very creative at all. I am very good, however, at synthesizing what others have done, with the occasional appearance of something new. But I rarely come up with truly original things. I think it may be an INTP side effect.