"Well, you see, I would help you clear my farm of those nasty trolls and save my daughter. But, as you can see from the fact that I'm holding my arm and panting, I just can't offer any assistance whatsoever. But, don't worry, once you've killed all the bad guys and their boss, I'll come running up just fine and reward you with some sword you can't use and a pittance of gold. If this amazing offer tempts you, random stranger who happened along, then my farm is just up the road. I'll just wait here, holding my arm and trying to catch my breath."