[ How does she stay calm...? It feels like answering that should be simple. Fighting is scary, but she feels like her nerves have been worn away. They're not as sensitive as they used to be. Part of it is that, and part of it is simple experience. But instead of any of that, Homura decides another way to answer. ]

Failure is not an option. And often, the key to making victory possible is staying calm. It's a decision and I've simply decided.

[ Though it's not detailed, she's being honest. It's an active thing she does rather than something that comes completely naturally. She's an anxious person normally. ]