In Psalm 95 the people are instructed to not harden their hearts.
The NIV Study Bible further elaborates with this study note:
'A hardened heart is as useless as a hardened lump of clay or a hardened loaf of bread. Nothing can restore it and make it useful. The psalmist warns against hardening our hearts as Israel did in the desert by continuing to resist God's will (Exodus 17:7).
They were so convinced that God couldn't deliver them that they simply lost their faith in Him. When someone's heart becomes hardened, that person is so stubbornly set in his ways that he or she cannot turn to God.
This does not happen all at once; it is the result of a series of choices to disregard God's will. If you resist God long enough, God may toss you aside like hardened bread, useless and worthless.'
Winners have soft, malleable, compassionate hearts.