Maximizing the cost-opportunity of my energy, limiting the risk of a burn-out

[Context: M<40 living in Italy near Milan, working an intense and stressful full time job]

I’ve always noticed that I experience spikes of energy and focus, followed by low moments where I feel tired and unmotivated. Until this summer, everything was balanced enough to keep me safe and functioning, but recently, as I’ve been working on multiple projects, I’ve started to feel like the overlap of all the energy spikes needed to sustain each project has pushed my low moments much closer to burnout than they used to be.

One of these projects is a personal (though anonymous) blog on personal finance and urbanism. In it, I decided to write an article arguing that my strategy to address the issue would be to "Overwork, Hit, Underwork, Repeat."
You can find more details on my theory in the article here.

The point is, nearly six months have passed since I posted the article, and my strategy clearly isn’t working - at least not so far. That said, I still feel the strong need to maximize the cost-opportunity of my energy...

So, what can a goal-oriented person, managing multiple projects at once, do to ensure that their drive for success doesn’t come at the expense of their personal life and mental health?

What do you think of my theory? Has anyone adopted a similar system to balance things out?