Some of what you say doesn't contradict the author. You might also have an incomplete understanding of some others.
(1) A prevention and a promotion focus are two types of focus people have a disposition to. You can't adopt a prevention focus if you are promotion inclined. Maybe you, personally, work better with tasks requiring a promotion focus.
(2) The technique you mention does not contradict the author. I agree with you though that often tricking your mind into starting something works wonders.
You can't ignore that having a process is tremendous help.
Murakami describes his writing process as an extremely rigid daily routine: he wakes up at 4 a.m. every day and writes for five to six hours, exercises in the early afternoon, and then reads or listens to music before his 9 p.m. bed time. Murakami adds: “I keep to this routine every day without variation. The repetition itself becomes the important thing; it’s a form of mesmerism. I mesmerize myself to reach a deeper state of mind.”
(3) Have you tried writing down your if-then plans? Because there's a huge difference in outcome between saying you will do something and writing down you will do something. Writing makes you commit. It keeps the unconscious mind away from sabotaging your decision.
If you're wondering why 3% of Harvard graduates make ten times more than the remaining 97% combined it's because they didn't just think of their plans but instead wrote them down.
http://sidsavara.com/personal-productivity/why-3-of-harvard-...