I noticed with Aizawa, when he stops looking so tired and aloof, and when his face shows nothing but pure fear, is when he ends up looking closer to his teenage self
He's scared and you realize how young he actually is sometimes, especially when he had to put his hair up for the news that one time? Because while I know his rugged appearance makes him look a ton older, 30-31 is still very young! He was 29 when the series first started with Deku in middle school!
You can really tell his age in these panels (that the anime didn't really seem to capture):
















