Excellence is doing the best you can at whatever you’re doing while simultaneously learning how to do it better the next time.
With that definition in mind, excellence is attainable every day.
What’s not attainable is perfection. Focusing on being perfect is both a waste of time and a dangerous emotional activity. Since it’s an impossible state to ever reach we can put ourselves in a constant state of depression if we make perfection our goal.
Just try your best, and then try to get better. That’s more than enough of a challenge.