Be water, my friend

I came across this book Fluid BJJ on Amazon 
https://www.amazon.co.uk/Fluid-BJJ-Scrawny-Ge…/…/ref=sr_1_1…. The author is a third degree black belt under Renzo Gracie and Jon Danaher, and trains with GSP and Firas Zahabi. In the intro he says: “I believe water drilling has been instrumental in my ability to train seven days a week while continuing to improve my skill set through: mental (imagery) rehearsal which allows me to build up muscle memory and perfect technique while having an ‘easy’ day; repetition/ drilling that does not severely tax my body; and water qualities which improve overall fitness and lower the gravity or training partner’s pressure on my joints”…OK some of it looks like water aerobics, but maybe it’s worth trying https://www.youtube.com/watch?v=ziAYV8ayk9M