When you stop even thinking about or worrying about if/when you get tapped out, you will truly start to transform your training.
When "winning" becomes simply hitting the transition or the sweep, or the guard pass you've been practicing, you will begin to warp your training into overdrive.
When you defend and cling to the notion of not getting tapped out rather than training and trying the components of your game, you absolutely kill your growth.
Willpower will only carry you so far.
Willpower, ultimately, fails.
Unrelenting pressure will break down virtually any machine.
Not to wax poetic, but water dripping on stone eventually breaks it down.
Berating yourself as weak every day in training and applying the weight of the world on yourself will not make you a diamond.
If you're serious about BJJ, you're likely physically and mentally overtraining in some sense of the word.
There is a point of diminishing returns.
You train to the point where your mind and body break down under duress.
Your self-image falters, or perhaps reaffirms insecurity and self doubt.
Frustration further cripples your belief in your ability to apply X technique or Y guard pass.
The days in which you allow your subconscious Jiu-Jitsu to come out. You operate in the "flow" or "go" state like Rickson mentions.
I find that I do not progress as well if I operate with a play day mentality every training session. If I go to the gym always willing to simply "see what happens" I inevitably work my closed guard to a sweep or submission because I inevitably revert to what I feel comfortable and where I can find moments to rest.
When I decide a position or a sweep I want to reach and become comfortable with, I find myself putting puzzle pieces together more frequently than not.
Again though, the unrelenting grind of trying to force the same position or sweep or pass will cause it to grow stale, unappetizing, and you will eventually grow bored.
Bottom Game Progression:
Reverse De La Riva - to account for lack of flexibility in my left leg after ACL surgery
Deep Half - when they bypassed Reverse DLRiva by pressing in
Spider-Guard - when they retreated by backing away
De La Riva + Spider Guard when in mid-range, and more comfortable switching between guards
De La Riva to Leandro Lo X-guard + Spider Guard - more comfortable with position and now forcing/hunting for the sweep to come up on top