Term or Title That Embraces the Juxtaposition of Work and Fun

Solution 1:

A clever way to approach this:

Part 1: Title of respect

Admiral:the commander in chief of a navy; a commissioned officer in the navy or coast guard who ranks above a vice admiral and whose insignia is four stars

Captain: a military leader : the commander of a unit or a body of troops

Chief: accorded highest rank or office

Above definitions Merriam Webster

Part 2: Work Hard

Efficient: someone who is efficient works well and quickly and is good at organizing their work in the way that gets the best results

Productivite: working hard and producing or achieving a lot

Diligent: someone who is diligent works very hard and very carefully

Above definitions from Macmillan Dictionary

Part 3- Play Hard

Leisure: freedom provided by the cessation of activities

Entertainment: amusement or diversion provided especially by performers

Recreation: refreshment of strength and spirits after work

Above definitions from Merriam Webster

End Result:

Admiral Productive Entertainer CELO- Chief Effective and Leisure Officer Captain of Dilligence and Recreation

Solution 2:

How about...

Dynamic

2. (of a person) positive in attitude and full of energy and new ideas.
   a dynamic young advertising executive

This can be said of someone who has the energy to carry on their work as if it is a fun thing to do, while very dedicated and tuned in.

Maybe also...

Lighthearted yet dedicated

Lighthearted

1. (1.1) (of a person or their behavior) cheerful and carefree.
   excited, lighthearted chatter

Dedicated

1. (of a person) devoted to a task or purpose; having single-minded loyalty or integrity.
   a team of dedicated doctors

This, to me, would imply someone who is a hard worker with a light personality to enjoy the work.