What has been the most life-changing experience you've ever had?

We all have many of them throughout our lives.
For instance, you start out the door and realize you forgot your wallet. So you go back in and get it. You have delayed your leave-taking for perhaps 30 seconds.
Down your street two cars collide.  
If you had remembered your wallet you would have been one of them.

Anyone who has ever become a parent has had a pretty noteworthy life changing experience.
Or gotten married.
Or bought their first home.
Or won the lottery.

It's all relative.  
Each day changes us to some degree with its life experiences.