I understand what you mean about work vs. worship, since Mr. Lewis records that prayer as he first understood it seemed laborious. But there was more to it besides. If his mother had not died of sickness when he was young, he would not have experienced the bitterness against God which pushed him over the edge for years. Having Digory's mother get cured in "The Magician's Nephew"--the very request that had been denied to the boy Jack Lewis--Mr. Lewis was working out his old childhood grief. Kind of like the movie "The Never-Ending Story," in which the boy Bastian, when called upon to give the Child Empress a new name, gives her the name of his deceased mother. (Which, in a further thought, was one of the many things done all wrong in the sequel to that film: they forgot or ignored the naming of the good Empress.)
Moving to another fact, did you know that Mr. Lewis once had a REAL swordfight? I read this in one of his biographies. One of the young men having private teaching sessions with him was being stubborn about some question that Mr. Lewis felt sure the lad _should_ have seen his way; so--perhaps with a hidden intent of introducing the student to the old-time concept of duels of honor--he challenged the younger man to a duel-to-the-first-touch with real swords. The student took him up on it...and received what perhaps was a useful lesson in respecting his elders, when Lewis won the match.