Based on what you wrote, it appears that you are not familiar with the motto: "Do not work harder - work smarter".

Admittedly, there are situations that simply require elbow grease, so I am not discounting the need to try hard - at times.

Still, in today's world, given all the complex challenges, if you do not adopt the "work smarter" approach, regularly reviewing your progress, determining what is working and what is not working, discarding the methods that are counterproductive, etc., you won't get out of the rut you are describing.

If you have bipolar, some of the roller coaster experience can be explained by the diagnosis and going from an elevated state to a low energy state and back. I highly doubt, though, that the whole roller coaster experience is explainable by bipolar. I bet at least a good portion of the roller coaster is due to the fact that you do not know how to work smart, to break down work into doable chunks, to analyze your progress and adjust your methods.

Let me give you a trivial example from my life that illustrates the point.

I could not get my counters clean using Fantastic bubbles no matter how hard I tried. I asked a resident cleaning expert on the bipolar forum who knows how to clean for real and she advised me to buy a degreaser. A short trip to Target and I have Clorox degreaser in hand. A few sprays and a bit of wiping and the counters are clean (I can show pictures of before and after).
Did I work hard? No, I worked smart - I asked an expert for product advice and implemented it. The expert explained that Fantastic does nothing useful - it only looks good on commercials.

I realize that this might be trivial, but I wanted to illustrate with a small and clear point.