Thinking about work can be exhausting, even if it’s work you love doing.
If your brain floats back to it and you end up doing a couple of things on your phone of an evening before you know it you’ve spent an extra 2 hours thinking about work.
And the problem I’ve found is that thinking about work can be just as tiring as doing actual work. Only, when you actually do work it’s productive and you can get results and move forward. Whereas, if you’re thinking about work but not implementing anything you’re going nowhere but still tiring yourself out leaving you less motivated for the next day.
As I’m sure you’ve guessed this is what happened to me last night, but I think I’ve thought of a solution for next time. If an interesting thought comes through your head of an evening, go and write it down somewhere, do whatever you need to do if it can’t wait, then stop and turn the work head off.