If you start noticing this in your colleagues: "... rigid, humorless, inflexible and closed to trying out new options.", then please get them into playschool ASAP.
"The differences in playfulness when adulthood arrives (I have followed more than 6,000 detailed play histories) validates the importance of lifelong play. Play-deprived adults are often rigid, humorless, inflexible and closed to trying out new options. Playfulness enhances the capacity to innovate, adapt and master changing circumstances. It is not just an escape. It can help us integrate and reconcile difficult or contradictory circumstances. And, often, it can show us a way out of our problems. There are numerous examples of difficult, deadlocked negotiations that were broken open by a joke or humorous incident. Many people have had the experience of coming back from vacation brimming with new ideas for work. The benefits of play come not from “rest” for the brain, as if play is just a time-out from life. Play is an active process that reshapes our rigid views of the world."
Fortunately for me since I'm a bit of a workaholic is that for me work is play. It's not just an adventure - it's a job!