Reading theory for starters. For long stretches of time, I just don't have the mental bandwidth. Working, trying to find a new job, etc seem to leave me mentally drained more and more frequently.

Learning new things, developing hobbies, meeting new people. Going to the gym regularly or eating healthier. I have limited time and energy at the best of times.

For a recent example: I opted out of a reading and discussion group I'm really interested in, in favor of reading and learning about writing resumes and doing better in job interviews.