The mental health/conditioning piece was only part of this story. The devoting Fridays to physical recovery versus practice was what I found interesting. It says the Packers' conditioning coach convinced McCarthy of this. I'm curious what the basis for it is. I don't doubt the validity, just curious about the research/science behind it.
The stuff about not getting too high or low is also interesting. There's a lot of talk about teams getting "up" for games, and locker-room material, etc., and I tend to think all of that is mostly garbage. When you're too hyped up, you're as likely to overthrow the ball or overcommit to your gap, go for the big hit instead of the sound tackle, make those kinds of mistakes, as you are to play better. In a "do your job" league of professionals, staying focused on doing your job right play to play is way more important. At lower levels of play, that stuff might be a differentiator, but nobody's making it to the NFL without being able to get themselves up for game day.