Hi- I'm just wondering how abstract Boggarts could be/ what sounds stupid. Like Hermione's fear of failure was shown by Professor McGOnagall telling her she'd failed her tests, and Harry's fear of fear was shown by the dementors. But what about other "concepts" as opposed to exact things?

Like one of my characters fears failure and being trapped in a monotonous cycle. Now at the moment I've got this being him trying to push a rock up a slope, and the rock falling down before he reaches the top. Is this too stupid/ abstract? Any other possible suggestions?
ANy help/ advice would be great thanks!