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."
Term popularized by sportstalkjoe and his followers on Twitter, used to describe something that is particularly unpleasant, hard to watch, or difficult to deal with.
Me: “Hey SportsTalkJoe, find a job yet?”
SportsTalkJoe: “Nope, too busyinjectingmarijuana into my ass”
Me: “Tough Scene”