Cable disc brakes. I kept putting it off but it was riding like shit and didn’t feel safe, brake levers nearly contacting the handlebar. I had it in my head that the adjustment was like a 30 minute job. Grabbed Allen wrenches, a couple third hands, screwdrivers. 5 minutes and two Allen bolts later, all done. Topped off the tires with air, quick test ride, meat’s back on the menu. No real point to this post, but maybe you’ve made a quick adjustment or repair that made you happy?
Had to replace a gear shifter on my road bike recently, not being aware that I’d have to replace the whole cable to do so and then calibrate tension for the derailleur, but similarly to your experience, the whole thing was easier than expected! Folks should definitely try such repairs and maintenance at home to get to know their bikes better, and it’s not like it’ll cost more to get a pro to do it after you’ve tried (carefully), if it turns out you can’t get the job done yourself.