From the Comprehensive Rules 4.0:
Sometimes you may exert a character by placing a wound on that card to show that the character takes an action that depletes his vitality. If the cost of an action requires a character to exert X times, then that character must have X+1 or more vitality or that action cannot be performed.
Exerting a character is different from wounding a character, even though both require placement of a wound token. Cards that prevent wounds cannot prevent a wound token placed by exerting.
See also exhausted, for each, healing.
|General||At Random||Can/Cannot||Cost||Effect||May||Limit||Pass||Prevent||Spot||Up To|
|Triggers||At the Start||Each Time||When||While|
|Phase Actions||Assign||Cancel||Special Ability||Response|
|Site Actions||At a Site||Control||Liberate||Replace|