I leave things that I know I cannot control

Waiting for test results, or for a reply from someone who is still deciding, produces one very particular activity: refreshing a page that has not changed. You know it has not changed. You do it anyway, roughly every four minutes, because doing something feels better than doing nothing even when the something is nothing.

That refresh is what holding on actually looks like from outside. Not noble persistence. A thumb, moving.

Leaving a thing alone is not indifference and does not mean you have stopped caring how it goes. It means you have accepted that your caring is not one of the inputs.