when Naruto was 13, and he could be honest about his fears and insecurities only with Iruka, and would still yell how strong he is in front of enyone else for many chapters more, acting insulted when they don’t belive him, or don’t cheer for him, or don’t give him a chance,
when he meets Hinata on training field before Neji’s fight, and she thanks him for cheering her on and giving her strength, he basiacally says to her, Hinata, to be honest, I am not strong at all, I am failing all the time, and I am full of insecurities, and if you, for real, think those nice things about me, don’t
He drops his i’m the best!! act so fast, I’m never going to stop being stunned about it - Naruto at 13 felt safe to be weak in front of Hinata. He’s serious and honest with her and just puts his core right there in the open - i’m just acting tough, I feel weak, I am frustrated about my constant failrues! And he does that, because he thought she was cool in fight with Neji. He thought she won the fight if not the match, and he didnt want her to lessen her strength by pinning it only on his loud mouth. And also, he’s scared about losing Neji now and thus dissapointing Hinata. AND DOESNT IT JUST CRUSH YOUR SOUL?
And then she says to him, No, all this time, it’s not your failures I saw, but you standing back up, and it’s exactly why I think you ARE very strong
And it’s not only one of the biggest prises Naruto got at this point of the manga, it’s that moment when other person sees him. Naruto is not only elated to be called strong, and to be honestly belived in, he probably realises that all those times Hinata was quaet and weird and nice to him, all those times she knew he had insecurities and failed all the time and was frustrated with himself - and she never laughed or ridiculed him for that, but honestly thought him strong.