Next Build Your Capacity
Like any skill or muscle, conscious practice and repetition increases your ability to perform the skill on command. A calm nervous system and mind is a skill you can develop, no matter how busy and chaotic your schedule.
I recommend starting with the 1 minute audio, practice with it each day for 30 days or until it feels easy and automatic. Then move to the next level again for 30 days, and so on. I've created track with music and without depending on your preference. There are also two sleep tracks at the end if your mind races when your head hits the pillow.
Slow and steady practice builds the strong foundation you'll need to be able to stay calm under pressure, get calm on command, and stay centered for extended periods of change and chaos.