Reported
What practitioners describe.
Tim Ferriss's audience made the method a biohacker staple. It costs nothing and measures well.
Protocol
How to practice for this.
Breath
Three to four rounds each morning, seated, on an empty stomach.
Cold
End the shower cold; progress by degrees.
Commitment
Thirty days. Track it. Notice.
Safety, plainlyNever practice breathing exercises in or near water.
Personal experience, not medical claimsReported benefits are personal experiences; consult a physician for any medical condition. Read the safety doctrine.