The ideal state is basically the ‘zone state’ which can also be described as the state of ‘restful awareness’ or ‘restful arousal’. The chances of getting in this state can be improved over time but transcending based meditation practices. My major recommendation would be to look into doing Transcendental Meditation or TM. This is what I did at the start of my career, and a large number of elite athletes were doing it back then as they are today.
There is a description of the meditation we did in the seminar at https://www.markbunn.com.au/meditation_breathing/.
The other thing is to practice what is called ‘Pranayama’ breathing. You can do this before the meditation but also I think it would be great while sitting in your car before the race etc. It balances both sides of the brain, calming mind and body and focusing the mind. Perfect.
I don’t have anything in written form on it but if you Google ‘Pranayama breathing’, you should get loads of information.
Hope all that helps and good luck with it all. Let me know how you go.
* Chapter 4 of my book which is on the true purpose of exercise, touches on some other important principles of exercise and sports performance which can help.
Yours in good health