Actually - my take on this is that it was/is a way of motivating students to keep this as the highest priority, as the most important thing, as he knew it is.
In other words- don't stop your releasing because you decide you want to run a marathon. Put all your energy into the releasing, because this goal is more important than the marathon goal. But, if you are in the state which many of us are where it is hard or impossible to see that goal as more important than the "material" goal, the idea of "i can achieve this goal by releasing only" will keep the releasing happening.
No coincidence that I came across this minutes after writing:
around 8 minutes in.
Well i think that is possible, only obstacle is that we think that we cannot. Due the fact that we are tought the way that we cannot.
I believe there´s no restrictions, only we are that restriction.
We can either do it or we do not do it, it is oure choice. Sadly a bit hard one to look into it and accept that.