Thanks, BitMoreRightRudder, that is helpful. That's pretty much what I thought - if you have thought hard about what you need to be, the likelihood is you'll already have taken steps towards becoming this and have some idea of how to continue developing into the role.
When you're dealing with the unknown it's tempting to think a little too hard about everything in your anxiety to get it right, which I think is the real problem. (Rather than failing to have a sensible thought in my head...
)