Great Expectations
In the vein of disappointment, I have another question: Where are you setting your expectations? I think for most of us, the answer to that question is, "too low."
When you're investing in something, or more particular, someone, set your expectations high. You're investing in them because you see potential. And they're allowing you to invest in them because they believe you can cultivate that potential.
When you let them off the hook with half-ass work, you're doing them a disservice. It's easy for us to say, "That's all right, everyone fails sometimes." And there is certainly a time for it to be said. But more often, we should be saying, "Go back and do it better." If you prefer, you can preface it with "Good work."
It might come off as insensitive, but in the end, higher expectations mean better results. Whether you're in the business of creating products, delivering services, or developing individuals, that's a win-win situation.
When it comes to people, expect work, products, and character just a little bit better than you have ever seen from them before.