Appropriate amount of effort is the least required to make it work. Without effort object would fall to the floor because grip was too weak.

One reason why performance of a master (art, music, sport, whatever) looks so effortless is because of crude and unforgiving practice.

Your definition is more correct.

I'm close to some kind of mastery with cello, and broadly we tell students to play with zero tension.

This is useful to say (often they have way too much tension and need to really dial it back), but in reality there is _some_ tension in everything:

- left hand: the fingers are basically a conduit for your back weight, but they need enough strength to stand up and _act_ as a conduit, otherwise they'd collapse. (but they needn't do more)

- right hand: weight flows from the back, down the arm, into the index finger, and all power derives from that + bow speed + how close you are to the bridge. However, the thumb needs to engage enough to counterbalance the weight on top of the stick, otherwise the bow would clumsily fall over.

The key is, as you say, doing the bare minimum.

"Let me share my slightly unusual definition of “effort”: it’s the felt experience of expending energy beyond what an activity requires, like tensing your brow when you try to understand something, or the excess tension in your hand when you hold your phone...Using this definition, it’s clear that the appropriate amount of effort for any activity is zero."