I have often attempted to conceptualise the flow state that jiu-jitsu allows one (after some significant mat-time) to tap into.
I recently came upon this excerpt by Ian McEwan from his novel, Saturday. I think you would struggle to find a more perfect summation of what is, for me, the most gratifying thing about training BJJ:
“in a dream of absorption that has dissolved all sense of time, and all awareness of other parts of his life. Even his awareness of his own existence has vanished. He’s been delivered into a pure present, free of the weight of the past or any anxiety of the future. In retrospect, though never at the time, it feels like profound happiness. It’s a little like sex, in that he feels himself in another medium, but it’s less obviously pleasurable, and clearly not sensual. This state of mind brings a contentment he never finds with any passive form of entertainment. Books, cinema, even music can’t bring him to this. Working with others is one part of it, but it’s not all. This benevolent disassociation seems to require difficulty, prolonged demands on concentration and skills, pressure, problems to be solved, even danger. He feels calm, and spacious, fully qualified to exist. It’s a feeling of clarified emptiness, of deep, muted joy.”