The sacrifice acceptable to God is a broken spirit; a broken and contrite heart, O God, Thou wilt not despise.
Contrition is the second element of a good confession. It is part of the typically Catholic insistence of a marriage between word and deed, spirit and flesh, inner and outer. If you confess but don't mean to change, your confession is just a show. If you claim to have undergone a change of heart, but then refuse to confess your sins or change, you're just kidding yourself. By far, contrition is the most important element of the sacrament. If you are truly and fully contrite for your sins, but get killed in battle, or run over by a bus, or struck by a meteor before you get a chance to go to confession, you are still fully forgiven by God. But, of course, if you are seriously contrite and none of these somewhat improbable occurrences befalls you, then you should get to confession. And, wherever you are, you should pray the prayer of the psalmist: "Create in me a clean heart, and renew a steadfast spirit within me!"