Meanings of fresh youthfulness in English

She was shamed by the fresh youthfulness of his slender, eager carriage and of his eyes.

Through his own fresh youthfulness, once so winning and wholesome, something pinched and cloistered had begun to thrust itself.

She, whose memory still distressed him after twenty years of penitence, had the same fresh youthfulness, the same proud expression, and the same lily-like grace.