Toughness is often thought of as being a physical characteristic. While being physical tough is certainly important, in the real world, it is not the only requisite; you must also be mentally and emotionally tough. Toughness is not no just being able to resist physical, mental, or emotional stress; it is also being able to recover quickly from these stresses.
I had a Shiba Inu dog that weighted 25 pounds, looked like a miniature Akita, and was so adorable that, when people saw him in the car with me, they would stop me in traffic to inquire about him. However, he was also a very dominate male. When any dog, no matter the size or temperament, approached him, he never showed fear. He just stood his ground and displayed the behavior that let other dogs know that he was the boss. He did not want to fight them and they did not want to fight him; they just knew from his demeanor that he was not to be messed with. Submissive dogs were allowed to approach him, but other dominant dogs just walked away. Toughness does not mean you are violent; it means you will not submit to violence. When you are tough, violent people sense it and tend to leave you alone.
Toughness is associated with talent and skill. Talent is a genetic propensity that defines the upper limit of your physical, mental, or emotional toughness. It is something you are born with, it cannot be acquired through training. You may never have used it but it lies away in your inner being, similar to a sleeping lion, waiting to be awakened for battle. If you choose to use a talent, it may be developed through skill training.