Succeeding at a PhD isn’t just about hard work and productivity.
It also requires creativity and imagination.
You do not have to be productive all the time.
Sometimes it’s good to slow down.
Or to stop.
Step away from the computer, leave the phone behind, get away from external distractions.
And just give yourself time to think.
To think with intense focus about a difficult problem, or to relax and daydream and play with ideas.
It’s when you feel you don’t have time to slow down that this is most important.