There is one main indicator I’ve noticed that shows when I’m in a productive flow:
I start listening to jazz. It just happens. I first noticed it about 15 years ago, and it continues to this day.
There is another indicator, specifically related to music practice:
I search out YouTube for help because something isn’t working practice-wise.
However, this indicator has friendly fire enabled.
Because in a moment like that, I’m likely going to YouTube feeling defeated.
Something is wrong and I need advice to find a path to a solution.
You might find that path, but a problem like this takes a long time to resolve,
so you will arrive at the destination at an unknown time in the future.
Alas, having found what you needed (or not), you pack up your things and get ready to log off the Tube,
and do your best to quiet those unsure, anxious feelings about when you might finally arrive at that destination.
But before you make it out the door,
YouTube tastes blood in the water
and sinks their algo-fangs into you,
with a deadly attack of the flashiest, most amazing
1-minute musical performances you’ve ever seen,
because you searched “how to + on guitar/drums/bass”.
And you might think, God, I really suck!
Why even bother?
The moral of the story:
be weary of where you seek help!