How to make stronger enemies?

How do I make enemies have more HP? I’m trying to fight Termintors, but all of them die really quickly. Is there any way to make them have a lot of life so that it is more realistic?

You could use an NPC Control tool to increase/decrease health. I’ll look for one.

EDIT: http://www.garrysmod.org/downloads/?a=view&id=42000