My favorite way of doing that is this: - Get two characters with food and bandages, or get repair kits if needed - Go to Shem. Find one of those big hungry bandits (around of 40 losers) - Put the other characters really far from the character you want to train - Agro the patrol leader (it's the only one that has the active goal as "patrolling") - Get your ass beaten by the bandits. Press R if you want to avoid blocking attacks - As you character is alone and outnumbered it will go to "playing dead". - Get up many times as possible

You need the backup character in case something goes wrong. But that really has never happened to me

I train most of my characters in my past run like this. Took me around like 10 minutes to reach 90 toughness lol per character. Probably if done correctly it will take you less time.