If Toughness Preparation is consumed, it raise Constitution (Con). Alchemy herbs are needed to craft preparations (later needed for Alchemy). They can be located with Nature's lore and then gathered with a Sickle or Primitive sickle. The Mortar and Pestle tool is required to create preparations from the herbs gathered, which trains the Herbalism skill. Every player character has his own Herbs combinations that he needs to discover for his self.
Go to Herbalism if you want to find out more.