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Saint Augustine was age 31 when he repented and converted, after having heard of Ponticianus's and his friends' first reading of the life of Saint Anthony of the Desert.
It is never too late to repent. The only unforgivable sin is blaspheming the Holy Spirit, which means refusing to repent of your sins (because if you don't repent/ask for forgiveness then you won't be), also called final impenitence.