And whenever you notice you forgot to do this routine you immediately smile and congratulate yourself on noticing this, which of course means you're more likely to remember it next time.

Upvoted for this part. I'm not sure if reward for noticing failure is mentioned in most self-training routines, but it feels like an important missing piece to me. The normal reaction to noticing failure is some degree of self-loathing instead, which of course encourages putting the task out of one's mind.

Also I like the idea of simple self-congratulation as a reward. Most examples I see are things like "eat an M&M when you do what you're supposed to", which is useless if the thing you are trying to train is not eating junk food (or if you're like me and will munch through the whole bag without being aware of it).