The first note you hear is the one you play
Some Sub-Saharan African communities celebrate annual festivals that are preceded by a mandated period of silence (or quiet, at any rate) in which music-making is banned (source, source). I don't know much about these musical cultures but the general idea has been weirdly impactful for me.

I don't want to make any claim that this is a great discovery so I'll keep it short. I've found that after a few days away from playing music -- and especially if I haven't been listening much either -- when I go back to the instrument I feel like I have a lot to say, the sounds are pleasing and I'm less likely to start nitpicking my technique or messing with knobs and switches.
I know it's kind of obvious. If you're going to eat a delicious meal in the evening, maybe don't have a heavy lunch. Getting a little tipsy at a party is fun; if you do it every day you're probably not really enjoying it any more. For me, at least, a big social occasion is more enjoyable if I've spent the time before alone. The miniature version of this is that pause that often precedes performances in various classical traditions -- the moment when the audience falls silent, the musicians are ready to play and everyone waits.
If I "practice" a musical instrument every day as a kind of chore or routine, I find the same predictable problems tend to emerge. I'm not one of those musicians who can play for eight hours a day every day for years. I've heard stories of a young Keith Jarrett sleeping under his piano because he couldn't bear to be parted from it, or Coltrane bringing his sax with him on a grocery run so he could practice Slonimsky patterns in the back seat -- I don't know if either is true but the idea that a real musician is one who wants to be playing every waking hour is persistent. Not only heroically long practice sessions but daily consistency too is part of that mythology. I guess some people really do live like that but most of us don't function best under those conditions. Many of us, perhaps especially those with ADHD traits, need variety.
A period of abstinence sharpens our faculties as well as making us want the thing more. I think this may be a version of the phenomenon whereby a break from wrestling with a problem miraculously causes the solution to spring to mind -- the brain seems to do a lot of its own processing and I think sometimes you have to push things into the background to let that happen.
For me this translates into a few simple admonitions:
- If my ears are tired I stop playing or listening for a while;
- If I have a performance coming up, I try not to listen or play at all that day;
- Listening to music isn't a rest activity from playing music;
- Avoid background music and other unintentional habits around recorded music;
- Negative self-criticism is a symptom of fatigue and is completely different from the pleasant process of noticing and addressing shortcomings in technique, knowledge etc;
- Some days it's just not happening but it turns out that those days can be productively used to rest the ears in preparation for the day when it is;
- It's important to have something you do in complete silence.
The last one has been a bit of a surprise to me. The more time I spend in silence, the happier I am with my playing. Maybe this is all extremely obvious but it took me a while to notice it and work out how to use it to my advantage.
Perhaps a partner to this post would be one on long pauses within pieces of music. But while many twentieth century composers used very quiet sounds and longer-then-usual rests, and many of them talk about the importance of silence in their work, not so many seem to have made structural use of long silences. Here's an example by Somei Satoh that I heard long ago and took a long time in finding again today -- although this thought process has left me wondering whether longer silences might work even better: