
People who sent thank-you letters underestimated how good the receiver would feel and overestimated how awkward it would be. One specific appreciation (what they did, and what it changed for you), unpolished.
P Evidence: promising. Good studies, but small or few. Use it and keep checking.
Kumar & Epley 2018.
Not medical, legal or financial advice.
In The Ecosystem every framework comes with a daily action, a room that checks in, and the full library.