Following is an example of this in action...
As successful as they are this colleague had an epiphany. They discovered that by sharing some of the fun they had from their personal interests their normally austere business persona shifted completely. They became more interested and engaging. That led to them developing even stronger relationships and exponentially increased the level of trust of others. The biggest surprise was the increase in productivity with little additional effort.
This colleague works hard, always has done. An expert in their field, they exude confidence and are highly respected by all those they come in to contact with. While they enjoy their work and the benefits it brings, they don't seem to have much fun.
This colleague is totally focused. Everything they do is driven to build relationship, create trust and manage the invisible boundary between business and pleasure. Their professional life is clearly delineated from personal in order to stay focused and keep their private life private. A very common behaviour and attitude.