Youthful
Young Looking
い adjective
A young young thing has youthfulness on their side. Oh to be youthful and young looking again!
The reading is the reading you learned with the kanji. Same goes for the repeater kanji.
コウイチっていつまでたっても若々しいよね。
Koichi's really had his youthful appearance forever.
そのファッション、ちょっと若々しすぎない？
Don't you think that type of fashion is a bit too young looking for you?
私の祖母は九十代ですが、六十代の人よりも若く見えます。若さの秘訣は、若々しい気持ちでいることと、よく噛むことだそうです。
My Grandmother is in her nineties and she looks younger than some people in their sixties. She says that feeling young and chewing foods a lot are two big secrets to her youth.