I believe that one of the most powerful things I can say is “I was responsible for this and I failed but I won’t let it happen again.” I find it painful to say, full of tension and anxiety over how the other person will respond. There is a chance they’ll respond poorly and that probability gets higher each time I have to say it. But most likely they’ll take you at your word, understand that I’m human like they are and know that humans aren’t perfect and that things happen.
Avoiding responsibility destroys trust and goodwill almost immediately and ensures you won’t be put in an important position again.