I struggled with the same problem, the 8 hours of solid productivity a day is a killer after working remotely during several days. My solution for that is the Pomodoro technique, I wrote an article about that, hope you find it useful: https://medium.com/@marcochvez/how-i-get-my-workday-done-in-...
Thanks I'm glad you find it useful :) I'm planning to add more features soon, I will add a settings panel to configure pomodoro length and alarms. Yeah, it's my first JAMstack project, built mainly in React with Redux, I'm using firebase as db and netlify as hosting