mother to a neurodivergent child (well -- he's 25 now. But he and my friend's son share a diagnosis) and she was surprisingly blunt about it: If it's affecting his mental health, then he gets to quit. He's 14, he knows his mind and he's suffering.
She acknowledged that there's an extra level of encouragement necessary about trying new things, but once the new thing has been tried, especially past a certain age, it's doing more harm then good. And I get that. I was honestly happy to hear that clear-cut a response, because I did get the "keep at it" part of the conversaation. I struggle with that with my niece, too. Though she's not necessarily one to always quit.
My friend's son doesn't quit everything, I should note. Just hates team sports.