We’re acculturated and accustomed to holding a little bit back.
It’s a logical learned response to the expectation of being asked to “give 110 percent” after our first effort.
This expectation is designed into the engine room telegraph: full steam ahead is how you get from San Francisco to Pearl Harbor as fast as possible, but flank speed is the true boiler-bursting sprint speed used to dodge a torpedo.
Nothing and no one can go at flank speed all the time, or even for very long. (Not without risking a real blowup, anyway.)
But we can be mindful and intentional about when to push the throttle to the stops and see what we can really do at full exertion.