aka "When a measure becomes a target, it ceases to be a good measure." - Goodhart's Law [0]
I like this, a lot, but I feel like I'm going to start incorrectly applying this in too many areas. It's dead true, but also a bit of a catch-all for so many IT scenarios.
Only when the metric we're measuring and the dimension we're looking for improvement on differ. This concern doesn't seem to apply to measuring lung capacity.
If you tie the bonuses of the people measuring the lung capacity to that lung capacity, then you will make that metric less accurate.
While the measurement of performance is critical towards improving it, we need to be careful about how we incentivize that performance. As performance on a metric becomes more economically important, the less useful the metric is in actually measuring performance and the less real improvement can be gained by its measurement.