You harden the targets's bodies against the stresses of long travel. You halve the Damage caused by hustling and forced marching (see Pathfinder RPG Core Rulebook 171). In addition, for the Duration of the spell the targets ignore any fatigue caused by such travel. Once the spell ends, if the targets still have any nonlethal Damage caused by the hustling or forced march, they become fatigued, or exhausted if already fatigued.