'Hearts' in the Bible

Whither shall we go up? Our brethren have made our hearts melt, saying, They are a people greater and taller than we; the cities are great and walled up to heaven; and moreover we have seen the sons of the Anakim there.

and shall say unto them, Hear, Israel, ye are approaching this day unto battle against your enemies: let not your hearts faint, fear not, and do not tremble, neither be afraid of them;

he said unto them, Set your hearts unto all the words that I testify among you this day, which ye shall command your children to take heed to do, all the words of this law.