Take a line from SWG:
Players generate stress when they take damage, use skills, basically do anything except walk and talk. Since you should be planning your adventures, you should be able to determine the minimum stress the party generates. So, you can then plan pit-stops where they need to go chill in the pub, at the club, brothel, wherever, so they can start feeling like normal people again and reduce their stress points.
Bonus if you're in a system well-designed enough to apply negative mods as stress builds. d100 systems works well for this.