"You can still be happy with a job not-well-done, as long as you gave it 100%."

Although it sounds counter-intuitive, its not. There's a myriad of reasons why a project might fail that have nothing to do with the effort put into it. Your requirements might be fluid, your deadlines restrictive, your budget too tight, etc. These things are not new in any project, and in fact seem the norm. Its how you approach the challenge that makes the difference. If you give up before you start because you know you can't meet the deadline, then you've already lost. But if you can figure out some way to make it work, even if the end product is not what you want, then there is nothing to be unhappy about, especially if you can make it. It seems you can reach some sort of zen-like acceptance of being simultaneously happy and unhappy while being perfectly alright with it all.

At least, that's the conclusion that I've come to after completing the last project at work. We took a piece of turd, cut it up, mixed it around, put it back together and polished it up good enough for release. Its not the piece of poop I wanted to release, but given the contraints we had, I reckon we did bloody well to release something that didn't smell all that bad.