Increasing my capacity to do things and actually exist successfully has mostly been a practice of building a Operations Manual for myself. For instance, having a specific morning routine to shift into work is something I find both emotionally stabilising and immensely practical.
Right now, I actually perform that by getting to my desk at a specific time each day (currently an hour before I start my day job) and running a batch file on my desktop which creates a dated copy of a checklist template. Then, I work through that checklist, deleting lines when they're done.
This features a mixture of self-focused things ('meditate, or do a functional equivalent', 'read for at least 5 minutes') and practical, forward-looking things ('look at your calendar and task management software and write your daily paper schedule', 'fetch the physical files and books you know you'll need').
Once this is done, I shift into another protocol for cracking through my comms and admin. This is another batch file which opens a bunch of tabs and windows. I set a 30 minute time and just work through each, closing them when I'm done. The end of that time is spent working through the Trello board that contains all my admin/admin-adjacent tasks.
When the timer goes off, I finish up what I'm doing, and stop. Then, I usually have enough time to make a coffee before starting the day job.
The batch triggers are the key here -- doing them as a matter of course. That way, the content of each can vary (I changed out my morning checklist to better match my current day-to-day), while the fundamental habit remains.