Your mistake was to take the word "fun" literally. What he meant was some "possibly enjoyable" state which was different from the "bored comfortable tedium" in

Your mistake was to take the word "fun" literally. What he meant was some "possibly enjoyable" state which was different from the "bored comfortable tedium" into which he had settled in. We all have had similar experiences. When you have too much of the same routine however comfortable, your mind craves some "new" stimulus which will break the tedium.