Eknath Easwaran said this quote

A mind that is racing over worries about the future or recycling resentments from the past is ill equipped to handle the challenges of the moment. By slowing down, we can train the mind to focus completely in the present. Then we will find that we can function well whatever the difficulties. That is what it means to be stress-proof: not avoiding stress but being at our best under pressure, calm, cool, and creative in the midst of the storm.