system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When we really have to pee, why does walking or moving lessen the need "to go" in the moment?
gpt
Needing to urinate is something which can be suppressed by the sympathetic (fight or flight) nervous system activity, or becomes more obvious when parasympathetic (rest and digest) nervous system activity predominates.

Exercising shifts the balance towards the sympathetic nervous system.