These magical boots empower the wearer with several abilities at once. Wondrous leaping, water-walking, and even flying! Yet the boots possess an insidious curse upon them as well. A deep and almost unfathomable (by others) feeling of listlessness, boredom, and even apathy affects the boots' wearer at all times whenever they are donned. Magic will not dispel the effects.
And so while the wearer of the boots can perform great feats of action during combat or at other opportune times and key moments, they'll never really want to do so, complaining "Meh, what's the point of it all anyway?" or "I would fly up and save us all guys, but sigh, maybe uhm, soonish, mkay? Bit bored by this whole burning tower at the moment."
Naturally the boots wearer's fellow PCs will grow quickly frustrated with this arrangement. There have been numerous occasions when one angry PC literally tears off the boots from his companion's feet in anger, and dons them in turn, only to immediately suffer from the same effects.
The solution lies in constantly "motivating" the boots' wearer with successful rolls, involving threats, flattery, fiery speeches, or even bribery.