What is the Hardest Thing You've Ever Done?

My sister was asked this question in an interview and I've been thinking about it all week.  Thinking about what my response would be.
Like all of us, I've gone through some pretty hard stuff.  Pretty serious stuff.  But the answer I chose was not something that may seem like the hardest thing in my life on the surface, but I think it's the most true answer I have.
The hardest thing I've ever done was ending a relationship with someone I loved very much because the relationship was not going somewhere that was consistent with my values. The reason I'd say this was the hardest, is because I had to have the courage to self-inflict that pain. But I know that happiness isn't found in avoiding pain. It's found in living a life consistent with your values. :)

What's the hardest thing you've ever done?