Behaviour is the visible tip. Beneath it sit skills, then beliefs, then identity — and trying to change the tip without touching what is below it rarely holds.
Above the waterline: behaviour and results — what people do and what it produces. This is all anyone can observe, and it is what management usually tries to change directly.
Below: capability (what someone can actually do), beliefs and values (what they think is true and what matters), and at the bottom identity (who they think they are).
Telling someone to behave differently addresses the tip. If the behaviour is produced by a belief — that selling is pushy, that asking for money is rude, that they are 'not a numbers person' — the instruction is fighting the whole iceberg and loses.
The practical version: change is easier from the bottom up. Someone who comes to see themselves as the sort of person who follows up does not need reminding to follow up.