How the knight healed

Somebody gave me a book a while back and I just got around to reading it, the English title is "The Knight in the Rusty Armor". (apparently is a bit of a classic or at least famous? I previously wasn't aware of it). It is a kind of humorous fable, a very short book, you could probably read it in an hour or two. The story is of a knight who becomes rusted inside his suit of armor and can't get out of it, or even open the visor. The knight has previously spent his whole life fighting dragons and "doing good deeds" (a goodist) but is really bad at recognizing emotions or paying attention to his family. He becomes very, very miserable locked inside his armor, it's extremely uncomfortable. Eventually he hooks up with Merlin the magician who sends him on a quest, and with the help of a talking squirrel and bird, he discovers the following, which heal him and unlocks the armor, bit by bit:

- He comes to understand that animals "accept" and live in the moment, while humans "wait for" and "hope for" things. And that no animal was ever locked in its own armor.
- He gets stuck in a castle and can only find the way out after he spends time examining his emotions and "journaling" in a way - expressing aloud all the things he feels
- The first time there is some relief is when he cries authentic tears of sorrow, and a piece of his visor falls off, so he can at least feed himself now
- He recognizes that he always had low self-esteem despite his bluster, and had difficulty loving others because he had difficulty loving himself
- He recognizes that he was a "people pleaser" - he always did things mainly to impress others and gain their praise
- Even though he has become scraggly and hagard, at one point he is shown his true self, the true self of everyone being perfect and beautiful
- Near the end he has to pass a dragon which is literally named the Dragon of Fear and Doubt. He is terrified of it (he doesn't have any weapons on this quest) and at first fails because of his fear. But eventually confronts it and as he faces it it gets smaller and smaller, and he realizes it was simply an illusion.
- He finally is cured and his armor falls off when he "lets go" - literally lets go hanging from a cliff - when his inner voice tells him to simply trust in God and the universe to solve his problem.

Anyway, you don't have to read the book now since I told you the story, lol, but it is a great little fable, and I was just struck by the similarities in it to healing from TMS. I think it was written in the late 80s.