Can you manage your time?

Our minds are fickle, says Drucker:

“Man is ill-equipped to manage his time. Even in total darkness, most people retain their sense of space. But even with the lights on, a few hours in a sealed room render most people incapable of estimating how much time has elapsed. […] If we rely on our memory, therefore, we do not know how time has been spent.”

Peter Drucker: How to (Actually) Manage Your Time