I'm trying to think how I learned to moderate exercise. I think breaking my leg, being unable to walk, and going on short term disability really helped. LOL Not that I would recommend that method, but coming back from it, I realized that I could get that feel-good endorphin buzz from walking outdoors on a nice day, or 30 minutes of yoga, or 5 minutes of kettlebells. It didn't have to get to a "visions of your ancestors" level of exhaustion for me to experience the mood-boost and feelings of wellbeing. I could experience a similar but less dramatic "high" with much shorter and more mellow workouts. Of course, I didn't know that because I'd never consistently done workouts that were short or mellow.
Once I varied the workout methods and intensities more, I found that I got the best results if most workouts were a medium "phoning it in" level of intensity, just going through the motions without crushing or killing anything. A couple of workouts per week were even easier than that, stretching or mobility stuff. And maybe one workout every week or two was extremely challenging. This allowed me to be incredibly consistent for months and years without burning out, unlike those 8-week programs where every session was brutal and I usually ended up sick, injured, and exhausted. That is the opposite of healthy and fit! I moved like a rickety old person and had no enthusiasm for anything when I was overtrained. Every day was a monumental struggle.
Now, I really look forward to doing something fun every day. I know it will feel good, and I know it will give me energy, not take it away.