You know, that's a lot easier to formulate than to do. Remembering to make everything that succeeds first be stress and strain and doubt, and everything that fails to at first look. Interrupt what is about to be said with a change of pace, and switch off to complete the thought. . . .
Not to mention the charms of doing this while figuring out the dialog to use, and the scenic description, and the metaphors that will convey the action, carry the right suggestions for atmosphere, and fit the world view of the point-of-view character.
sigh. Practice, practice, practice. There's nothing like making it automatic to make it easier to work on them at the same time.