My work day starts early, and well before my day job begins.
I have always been a morning person. The quiet before the storm, or simply a guaranteed time where no one else is likely to be up. It's also the time I use to prepare for the many people interactions throughout the day. Peopling is tough.
One of the things I've learned, something that became very clear once I started taking night courses after work, was that I have a threshold of what I can handle each day. By the time I get to the end, I'm completely sapped. I might be able to eke out an hour of sustained attention after an outrageous amount of espresso, but I'm not at my best and this typically only works for less precise things. Discussions on philosophy? I can manage. Learning about human genetics? Not so much. The only recombination I understood was the chaotic layout of my exhausted brain cells as they collapsed in place like tiny drunkards.
Now that I'm done with school, all I have to worry about is writing and my day job. While I don't hate what I do for a living, what I absolutely love to do is write. I manage my energy reserves by putting my interests and passions first, and that means I get up at 3:00AM to get to work on my writing projects.
Some people prefer to get mundane things out of the way like exercise or chores, meal prep, etc. For me, those things steal from my energy bank. I also prefer to dive into writing before the self-doubt kicks in, or before the distractions of the world take their toll. Most importantly, before someone can interrupt my thoughts and make demands of my time.
By the time I need to start working, I've been up for 3+ hours, and my peak productivity is spent on what matters to me most: writing.
One day my day writing might be my day job, but for now, I manage by keeping the best of me ready for me.