Anders Ericsson is a professor of psychology at Florida State University and co-author of the book, Peak: Secrets from the New Science of Expertise, which you can find on Amazon and Audible.
Angela Duckworth is a professor of psychology at the University of Pennsylvania. She is the author of Grit: The Power of Passion and Perseverance which you can find on Amazon and Audible.
Staying hydrated is very important especially before races and practices when it is hot. If you are preparing for a race, you should be hydrating at least a week before and especially the day before.
You may also want to drink coconut water or add electrolytes to your water bottle from the Hydration Multiplier of Liquid I.V. or drink coconut water which you can buy on Amazon and Costco.
Check out the videos below on the importance of electrolytes to your health.
Check out the Headspace app which helps athletes meditate.
This is a video about running, but it gives some good tips for us paddlers.