If you believe in the power of positive affirmations, why not combine it with the security of strong passwords?
I believe in a couple of principles:
Long passwords can be both strong and memorizable.
Positive affirmations do work to improve habits and self esteem.
Writing or typing something is a better way to remember it than just reading it.
Here’s how I might combine these beliefs:
Start with an affirmation that makes sense for you, here is a generic cliche: Today is going to be the best day of my life.
Change some words to make the sentence illogical: Today was gonna be the super day of my lifes.
Introduce some more spelling and grammar mistakes: Todei wass gonna bee teh supahst dai ov my lifez.
Add digits and special characters: T0dei/wass\gonna B33_teh-supahst-dai,ov;my?lifez!1
There is a pass phrase that should be pretty secure against brute force and rainbow attacks and makes one think of the initially selected affirmation whenever it is entered.