In his article, PG was describing personal qualities, as opposed to external qualities (with something of an exception in the case of the cofounder item). In the case of most personality traits, if you want that trait and actually try your best to exhibit it, then "you believe it, you become it," is pretty accurate.
If you want to procrastinate less and right away you begin to finish things that you've been putting off, well then you've already won. But if you keep putting off the day when you'll stop procrastinating, well you can see where that's going.
I think most people underestimate their ability to hack their own personalities.
I don't know, there's too much room for self-delusion.
It's easier for an unimaginative person to convince themselves that they're imaginative than for an imaginative person to actually become imaginative. The illusion that you're King of England can't be maintained for long. The illusion that you're good-looking can be maintained for a little longer. The illusion that you're determined, imaginative and... naughty... can be maintained pretty easily.
If you want to procrastinate less and right away you begin to finish things that you've been putting off, well then you've already won. But if you keep putting off the day when you'll stop procrastinating, well you can see where that's going.
I think most people underestimate their ability to hack their own personalities.