Riding a bicycle in a hilly area requires good gear management. Once you are approaching a hill, you have to down shift to be able to continue pedalling. But if you down shift too soon or too much, your feet are spinning and you are't really propelling the bicycle forward. If not corrected, the bicycle will slow too much and you'll fall off. But if you wait too long to down shift, it's too difficult to keep pedalling, and the bicycle will stop and you fall off. You have to be pedalling at a certain speed to be able to shift gears, so once you're off, you have to go elsewhere to get started again.

EDIT: When there is a mismatch between effort and output, the effort doesn’t become more difficult, it becomes completely impossible.

I have inattentive type ADHD, and I struggle with switching tasks, especially if not by choice. I find work really difficult because it feels like I'm riding blind and I'll just come up to a surprise hill without the foresight to know I should be shifting gears until I'm already at an incline. It's also why I get stressed when plans change, as I can no longer see the road ahead.