Well, you do get the impression of real struggle and resolution in the Trio's decision in PS.

Dumbledore's statement does seem to apply to those not at the centre of the action, and also to operate as a sort of general statement to the reader. In OotP Harry, of course, tries to do what's right in his capslocks way and makes a pig's ear of it. Then in HBP he and just about everyone goes about doing stuff that's pretty much wrong and difficult!