Have you seen the weapons prisoners make out of soap, spoons, or whatever they can get their hands on? It’s amazing what you can do with limited resources, if you really put your mind to it.

A good business example: 
Southwest Airlines. The airline has succeeded in large part due to its embrace of constraints. For example, its fleet consists exclusively of aircraft from the Boeing 737 line. By flying only a single aircraft, the company spends less to train pilots, ground crew, and mechanics. And maintenance, purchasing, and other operations are also vastly simplified, which reduces costs too.

More ways that Southwest keeps it simple: It offers flights only to select cities, no seating class distinctions, a simple pricing structure, a bare-bones frequent flier program, no meal service, etc.

Shows how executing on essential functions and leaving the rest out can still take you a long way.