Say that you've been planning to knit a sweater for years. You've researched patterns, spoken with your grandmother who's a master, and you finally think you've reached the point where you're ready to begin knitting. You hope that your birthday present will be a set of knitting needles and yarn, but when you come home you instead find a Lego set.
Now, this doesn't mean it's a good idea to give up on your knitting goal. You obviously have a lot invested in it, and maybe the Legos can be exchanged for your knitting equipment; and in any case, there's a good chance you'll be able to get knitting equipment later on, somehow. But in stating this obvious fact (which is captured in the value of perseverance) one may lose sight of an even more obvious one: that the right thing to do in this situation is not to try to knit a sweater out of Legos.
One might say that the problem with knitting a sweater out of Legos is ineffectual means, albeit pursuing a worthwhile goal. But consider: totally ignoring the Legos might not be the right thing to do either. If Legos are cheap enough and the enjoyment you'd get out of playing with them is low enough, then maybe it is; but maybe your niece would love to have them, if you'd just stop and think about it. In order to even realize this, though, you have to pay attention to the Legos, which means diverting some of your focus from your knitting.
If your only goal was to knit a sweater, then it might truly be said that ignoring the Legos (without ever considering them) would be the right thing to do. But what kind of person has no goal other than to knit a sweater? A deeply impoverished one, I think most of us would say. Though the person possessed only of this one goal might appear beautifully simple at first, we would recoil from some of the actions he or she would be willing to take in pursuit of this one goal, if it was really his or her only goal.
In the case of mundane goals this intuition may appear obvious, but it becomes more interesting when applied to higher-level values. One common example is justice. In fiction, often a character who pursues only justice (forthrightly, not for personal gain) at first appears attractive; but eventually he takes actions that strike us as inhuman, and suffers or becomes repentent (or both). The ones who suffer without repenting are the ones who held justice as such a fixed star in their systems of value that they lost sight of other values.