TBH I'm not big fan of lunging. May be for little bit just to take some edge off and keep horse concentrated on you and its own hoofs, but not an endless, purposeless one. You can do plenty of other things on ground: bending, moving off the pressure, back up, side passing, etc.
"Life isn't about waiting for the storm to pass: it's about learning to dance in the rain..."
"When we are no longer able to change a situation - we are challenged to change ourselves."
"How people treat you is their karma; how you react is yours."