I've struggled with this for most of my life, and recently went on sabbatical when I, too, saw myself no longer able to perform, and I took myself out of the game before my personal struggles had a chance to force me out.
I think the post is giving questionable advice about the role of willpower in making the right choices. I think it is advising the use of willpower for challenges that may be better addressed in other ways.
If "life is a game", and willpower is a jetpack with limited fuel, the piece reads like a strategy guide that tells you how to best use your jetpack to go about routine tasks, and focuses on preservation of fuel to ensure you can keep using the jetpack for those tasks. It fails to ask the question: is a jetpack the right tool in the first place? Is the preservation of fuel just sidestepping a deeper and more fundamental issue? Should you really be using a jetpack to ascend a few flights of stairs?
I see my collapse at work as partly due to a misapplication of willpower to surmount obstacles that could be best bypassed by navigating around or through those obstacles instead of assuming that the only option is up and over. This was a perspective that I could not see while I was in the situation, but as I've gained more critical distance, I've started to realize that lack of willpower was not the primary problem.
Everyone is different of course, but for me, establishing a mindfulness meditation habit in the morning and then building a solid core routine of daily habits around that and around tested cognitive approaches to reframing problems has been a much more sustainable path.
I think of it as priming my mind to make hard decisions with less effort, thus reducing the need for willpower in the first place. And the impact has really felt magical. Things I could hardly convince myself to do even after mustering every bit of willpower suddenly started to become automatic and effortless - no willpower required.
This started with the most basic of things: doing the dishes regularly, eating better foods, going to bed earlier, etc. This habit loop has a cascading positive effect. Better sleep led to better sessions of mindfulness and more moments of experiential insight. This in turn led to even more pronounced effects and less "limbic friction" for daily tasks. The effect doesn't seem to be that you gain more willpower, but that the willpower required to complete a task is reduced drastically, because your brain has seen more clearly the cost/benefit of each possible path.
I suddenly found myself digging in to some tasks and problems that I'd been avoiding for months/years. I suddenly found myself believing that this set of foundational habits would become the core of my next work endeavor.
I should disclaim that I'm still very much mid-journey, but I've done the willpower thing and failed. Cognitive approaches that change how your brain weighs decisions seems far more sustainable, and leaves the jetpack ready for when you really do need to scale the side of a cliff.