My client realized that his burn-out was over the years a result of his extrinsic motivated and driven behavior.

Extrinsic motivation is reward-driven behavior. ...  Like praise, fame, and or money. Though, the unconscious rewards are the fear of not meeting the deadline or receiving negative feedback. Unlike intrinsic motivation, external factors drive this form of motivation. The question that you can ask yourself is… ”Do I behave this way according to facts and assignments that are aligned, or is this behavior a result or my assumptions of expectations from others?”

Energy drain
When tasks are carried out willingly and are aligned with the individual’s personal goals and values, they do not draw extra energy from the person and may even enhance energy in some cases. Energy is an important resource because it has been linked to greater performance and persistence. This is in contrast to situations when tasks are executed under a controlled motivation mode. Here people experience pressure to think, feel or behave in particular ways. This is found to be energy-draining and results in lower quality performance outcomes over time.

Intrinsic motivation has been found to be more conducive to creativity compared to extrinsic motivation. Research has also suggested that high levels of motivation may compensate for a lack of relevant expertise, insecurity, or creativity skills.

I like this quote from the Philosopher Erich Fromm:
"As long as anyone believes that his ideal and purpose is outside him, that it is above the clouds, in the past or in the future, he will go outside himself and seek fulfillment where it cannot be found. He will look for solutions and answers at every point except where they can be found- in himself."