The part about changing the environment physically to more easily enter flow (such as wearing uniforms in football) reminds of the simple advice of not working in the bedroom. It is the same principle: you gotta put yourself in ‘work mode’ somehow, and getting out of the leisure space is probably a good first step.
Though the author showed a bit of disdain towards the rationalization of flow, in psychology we learned a simple fact: the brain gets used to new stimulus pretty quickly, and that is part of the reason why we are so curious about everything. We are continuously chasing the high of first times. This is also applicable to the flow chart in the reading: as people surpass challenges many times, they have to seek new challenges in order to find that enjoyment again. Its sounds a little depressing, that we are always chasing something impossible in a sense, but this principle is core to human growth and is a big part of why we are practically every where on Earth today.