Speaking from my own experience:
Ergonomics matter. Surprise, 6 hours spent hunched over, or squinting, or with your arms unnaturally extended … will leave you feeling tired and sore. A chair and desk and monitor that fit your body are worth it if you can possibly afford them.
When you work on what … matters. There’s a whole book on this topic (it’s probably pseudoscience), but anecdotally I work way more effectively in the morning when doing creative or challenging, focused work. Afternoons are good for socializing or reading but I am not gonna be smart, sorry.
Tools matter. Flow is a thing, and it’s easier to achieve and maintain when the feedback loop between you and your tools is a tight one. Waiting 8 seconds for a new Google Analytics view to load … breaks you out of flow. Closing a browser tab with ⌘-W instead of using a mouse … keeps you in flow. Investing in good tools and learning to use them means Future You will be capable of amazing things.
Channels and policies matter. By default, Slack becomes an always-on, instant-response-expected flow-killer. Explicitly stating expectations about availability and reply time helps a ton. Choosing to use asynchronous video instead of Zoom leads to different levels of joy and effectiveness for everyone involved.