Analysis paralysis is a great way to describe what your feeling. When I have a lot of different projects or interests going on. I choose the one im most interested in first and follow it to completion. And everyone's definition of completion is different. Perhaps you're interest only went as far as far as to find the problem in that car because you are only interested in the troubleshooting itself. Whereas sometimes you may be interested in completely overhauling and restoring a vehicle then your completion would be when the project is completed and the car is put back together. Either way the satisfaction you get to where your interest peaks and then falls is good enough. Then you can move on to the next project that brings you joy. Because at the end of the day we can only do what we enjoy to make us happy. and not stress about what's not interesting to us at the moment. Hope that makes sense and it's how I go about choosing different interests or projects. Basically just follow what makes you happy now until it doesn't