He tries to believe what she's saying. Despite his low self-esteem, he knows there's some truth to this. Steve knows he's been getting steadily stronger for a while now. Maybe it will be enough out there, maybe not. It means everything that going out doesn't mean losing her.

Steve has no words to thank her properly for it. He opts instead to close eyes, lean in further, and kiss her. He hopes it's enough to convey his gratitude.