Hezekiah trusted God to answer his prayer; he however, reminded God that he was loyal to Him thus pleaded that God would hear him.
Our unrighteousness can block the blessings God would shower upon us. An illustration is that of the open, giving hand. God says to share with others so that He might bless us. When we do, our hands are open in love and concern and He then can refill them. And He does, many times over.
When they are tight-fisted keeping all we have earned to ourselves, His blessings pass us by as we are not in a position to receive them.
Many blessings are not material but emotional, spiritual, things like love and friendship, health, family, etc. All good things are from God; we must be open to receive them. Praying to God in open trust, knowing His nature, we then are in a position to receive His good gifts.