Life is a long line of the unknowable. It surprises, upsets, beguiles, upends, and amazes. When we get up each and every morning (or whenever we roll out of bed), the day makes no promises other than, “I am here.”
So what you do, how you do it, the mental acuity you bring to each day – these things change. How well you do something, or recall what you knew, or learn and acquire new information – it can be different from day to day.
But just like that promise, “I am here,” so too should you be.