Lama Ole’s answer:
In principle, the levels of highest functioning, highest joy, and highest truth are equal. Experiencing greater happiness, seeing things as they are more clearly, and functioning better physically and mentally are intertwined. For example, if you work with proper tools in an interesting environment, then you are closer to the perfection of your nature than if you do something that won’t work with tools that are no good.
One just has to be careful not to get attached to the happiness but instead to pass the good feelings on to others. One has to understand that conditioned joys are impermanent.
We should always try to experience joy without an outer cause. Be aware that joy is inherent in one’s own mind, and try to let joy become independent from a cause as quickly as possible. Understand that joy is a moment without fabrication—without thoughts, without ideas, without any obstruction. In the moment one is naked and open, joy comes through. Try to reach that state without any outer influence. That comes through meditation; there you learn that your mind can find absolutely anything within itself and out of itself.