I think in auto mechanics, I accomplished things each day. Many beginnings and many ends. There was the mental challenges, similar to what I face these days, but those things came to completion much more frequently. It was rewarding.
Now my current job is absolutely rewarding as well. I’m actually recognized a lot for my troubleshooting ability, but normally a typical project from start to end could be four months - or more - if it includes a lot of documentation to pass off to an operations team. I definitely do more designing, documentation, and transitioning of those systems than I do troubleshooting, however these days.
Keep in mind, I’m not complaining - just explaining. I love my job and am challenged. I think it just misses some of the more frequent gratifying completion of tasks (which cycling fills).