Rule 38: Since poker is a game of positioning oneself to win (but with no guarantee of winning), there are going to be times when doing exactly

Since poker is a game of positioning oneself to win (but with no guarantee of winning), there are going to be times when doing exactly the right thing leads to losses.
There aren't many sports or games where you can have a lifetime of experience, make every play exactly right, and lose. But poker is one of them. This tells us something it tells us not to approach it like other games.
This is a difficult concept for some players to understand. They ask. «What am I doing wrong?» And if the answer is «Nothing», it leaves no rational explanation. Yet this situation is common in poker. Coolness must prevail. Clinical detachment and composure need to be embraced.

Rule 37: It's a mistake to use experience alone to determine what good poker play is.

Long-time experience can be deceptive. Our memory can be selective. It can mislead us, overemphasizing some things that occurred and underemphasizing others. A big win may shine brightly in our memory, yet if looked at closer, it might not be backed up by good play. Always make sure you are playing right first, and then get a lot of experience at it.
Don't do it in reverse. Don't reference your many years of experience
as proof that you mast be playing right. This kind of self-referential
argument is capable of containing numerous errors.
Similar card situations occur again and again, thousands of times. And some players have been playing them wrong – for years. Worse, such a player often learns to do so expertly! In fact, many of them become
excellent players, amazingly adept at «working around» their own flaws and weaknesses. They become experts at starting out with their own self-
imposed handicaps and overcoming them. They are like track stars who
become very proficient at finding ever newer and more innovative ways to
get over the hurdles that they themselves have put in their own way.

Rule 36: One of the main ways we improve in the game of poker is by getting certain lessons pounded into our heads.

Books, seminars, and other kinds of advice are all well and good, but
nothing instructs us in certain lessons like experience. Lessons learned
through painful experience tend to form a deep groove in the brain.

«You can close your eyes to reality, but not to memory». – Stanislaw J. Lec