The sacrifice acceptable to God is a broken spirit;
a broken and contrite heart, O God, thou wilt not despise.
St. James famously said that faith without works is dead. But, of course, the converse is true also: works without faith are dead too. In an age of lip-biting politicians who substitute going through the motions of penitence for an actual change of heart, real interior penance involves not just looking convincingly remorseful, but actually repenting your sin from the heart and resolving within to change. Such interior penance delights God, even if circumstances turn out to make it impossible to do anything about our change of heart. That's why the Good Thief was bound for paradise even though, hanging crucified, he could do nothing to recompense his victims. He'd had a real change of heart and was genuinely sorry for his sin. It was enough. Real interior penance is worth more than an infinity of token gestures.