Be living proof of something/that…
Definition 1 of 1
Pro Tip 1/3Clear Example
Use this phrase to highlight an undeniable example of a concept or fact. 
His recovery is living proof that the treatment is effective.
Pro Tip 2/3Positive Proof
It often implies positive evidence or confirmation that inspires or motivates others. 
She's living proof that persistence can overcome any obstacle.
Pro Tip 3/3Personal Testimony
Best used in contexts where personal experience or existence validates a claim. 
He's living proof that one can learn a new language at any age.