The act of putting into play
The use of energy to do something
Energetic physical action
Her face was flushed from exertion and anger.
His face blazed red from exertion, his eyes glowing brightly.
Talon's flush grew darker beneath the red of exertion on his face.
It needs no critical exertion to reduce utterly to dust any deductions drawn from history.
His muscles were still bulging from exertion of his visit to the gym, and her gaze stayed on his biceps as he pulled on his boots.