Most respondents here seem to be focusing on language/framework/tool choices, but decision fatigue is also much more fine-grained. Lots of people here saying to choose "boring" so that you supposedly don't face decision fatigue, however, even within a boring language or framework there are lots of decisions to be made as you develop software. If you're doing OO development, for example, you're constantly deciding what your objects/classes should be, what objects are responsible for what actions/tasks, what's the inheritance hierarchy(or maybe avoid inheritance altogether)? Even down to how you want to organize code into files. And then there are data structure choices: Do I want a linked list here, or maybe a binary tree would be better? I think a lot of folks here are saying "choose boring and you're decision fatigue goes away" but I don't think it's that simple.
Decisions about architecture, code structure, algorithms, data structures, etc. are an inherent part of software development. That's not a bad thing per se. And yes, you will experience fatigue - it comes with the territory - it's partly why we get paid the "big bucks" (for some value of "big"). The best way to deal with it? Take a break. Go for a walk. Get away from it for a bit. Soften your focus. Take some time to play - write some fun code for a personal project where it doesn't matter if you make a non-optimal choice. If need be, take a sabbatical for a few months or even longer if you're experiencing burnout.
(30+ year Software Developer)