But then the phrase just becomes generic advice everyone gives and provides an easy scapegoat to save face. Don't change it. Or if you must, you could at least dress it up a bit like Feynman http://www.basicfeynman.com/read_letters.html ("If you have any talent, or any occupation that delights you, do it, and do it to the hilt. Don't ask why, or what difficulties you may get into.") You can weasel your way out of failure with "well that's as good as I can be", it's harder to weasel out with "well I went at this at full force but failed anyway." The latter can also provide some satisfaction that you went as hard as you did, whereas the former just provides resignation.

(It's similar to Facebook's "Move fast and break things." It's a great phrase precisely because it's not the same generic advice everyone gives. There are times where it doesn't apply, that's more important than the times it does. Universal for all time advice sucks and is bland.)