What this means is that when faced with difficulties and adversity, those who are mentally and physically resilient do not give up, but formulate an effective and disciplined plan of action which they initiate and carry through to a successful conclusion.
"Despite getting stuck with the fallout from Malcolm's fuck-up, Nick got everything sorted inside of a week!"
"Yeah, when the going gets tough, the tough get going."
When a hidden or contained problem (the shit) is suddenly exposed or spirals into utter chaos (shit making contact with rotating fanblades) causing a change of tactic from problem elimination (disposal of shit) to damage control or abandonment (cleaning of all traces of bits of scattered of shit or escaping as situation is now unmanageable)
When the shit hits the fan, we’re going to need to call in a cleaner