When the option of running — in a fight of flight situation — is over, what do you do? Freeze up in the moment or prepare for battle. Depending on what you choose, can be a life altering situation, and with those kind of stakes, actions speak louder than words.
The most recent instance of this kind of scenario is Shingeki no Kyojin, with the back story of Ackerman Mikasa in episode six. Because of said back story, we now know why Mikasa is so protective of Eren — beside him being her only family left — Eren gave her something to fight and live for; she now had a reason to become stronger, and actually achieve it in the present — quite evident with how kick ass she is now.