When your skills aren't enough and leave you making mistakes and causing errors, what more can you do than apologize and try do better the next time? Nothing. You can do nothing about the accidentally offended person, and there's usually very little that can be done to fix what was broken. That's it.
So what about all of the time I should've been practicing piano or singing but didn't? I'm sorry; I can only apologize to myself. I am a promoter of productively wasting time, but when important things fall through the cracks and are replaced by wasteful things, that's when re-evaluation is needed.
And re-evaluation shouldn't just happen once. I need re-evaluation on a very frequent basis, but I don't get it as much as I should. Only because it's difficult; it's hard to do. So I fail sometimes, and sometimes succeed.