The people of Judah had 13 kings over more than 150 that did not follow through. The closest anyone came was Asa, who ruled for 41 years and did everything except remove the "high places" which had originated as places God was worship but had become corrupted. To his credit, he was "fully committed to the Lord all his life" even though he did not remove the high places (1 Kings 15:14).
Hezekiah, though, completely followed through after coming from a line of corrupt kings. His own father Ahaz sacrificed one of his other sons/Hezekiah's brother (2 Kings 16:3) following the ways of nations the Lord had driven out before Israel. This family is messed up. The writer of Kings doesn't go into how Hezekiah came to be strong in the Lord to stand up to the vast amount of wrong going on in Israel, but he did. He had backbone.
Here's where the stakes get raised. Hezekiah is being king and "did what was right in the eyes of the LORD, just as his father David had done" (2 Kings 18:3). The other kings all get compared with David, except that they were not as devoted to the LORD as David was; of the kings of Juday, only Asa and Hezekiah get this honor. He trusted in God fully, and is called the best king Judah ever had ("There was no one like him among the kings of Judah, either before or after him" 2 Kings 18:5).
He was highly successful until Assyria started to retake some cities that Hezekiah had taken back from them (he had cut ties to Assyria, the local bully who liked to take over other nations). Israel is deports all the people of the nation of Israel and then turns his eyes toward Judah. What happens next it not encouraging.
Fourteen years into King Hezekiah's reign, the King of Assyria "attacked all the fortified cities of Judah and occupied them" (2 Kings 18:13).
All the fortified cities of Judah. All of them. All of the cities that were fortified, e.g. not supposed to be taken over.
That's like hearing "So-and-so country/faction attacked and took over Washington DC, Chicago, New York, Miami, Los Angeles, San Francisco, Austin, and most other major cities in the U.S. You are now completely helpless."
For the sake of not giving away the spoilers that would give away how great this story is, I want to read 2 Kings 18 and 19. Hezekiah had backbone; he didn't give up even when his nation that he had stewardship of had been conquered except for Hezekiah's actual official surrender. Check out his response and what God did.