like he had spent thirty years in the world

[suprunp]

“Twenty-three. A full-fledged adult.”
“Of course,” Tengo said. He was already thirty, but yet to have a sense of himself as an adult. It just felt to him like he had spent thirty years in the world.
(H.Murakami; 1Q84)

What did the author mean by it?
Does it mean that he felt like he had spent thirty years in the world but still didn't feel that he had actually undergone some changes to become an adult?

Thanks.

[SoothingDave]

Yes. He didn't feel like he was an adult.