Penance is one of the seven sacraments that Our Blessed Lord established to give grace to His people. As every single human being who has ever lived, saving Our Blessed Lord,
…and His Mother, have been sinners, we all stand in need of forgiveness. The only sure way in which Our Blessed Lord established to have our sins absolved is in the sacrament of penance. So, as we can never be sure of obtaining forgiveness through an act of perfect contrition, the only way that we can be sure of obtaining forgiveness from God is through His Sacrament, without which we are condemning ourselves to hell for all eternity. . If you are talking about the act of penance instead of the sacrament, then to quote Blessed John XXIII:Doing penance for one's sins is a first step towards obtaining forgiveness and winning eternal salvation. That is the clear and explicit teaching of Christ, and no one can fail to see how justified and right the Catholic Church has always been in constantly insisting on this. She is the spokesman of her divine Redeemer. .No individual Christian can grow in perfection, nor can Christianity gain in vigor, except it be on the basis of penance. (MORE) 
