Mercy is that quality that no one deserves but everyone needs. It's that way in any realm and with anyone in a position to receive it in whatever capacity. The whole concept behind "mercy" is that someone, in a superior position to us, is willing to suspend any judgment or penalty, purely out of the kindness of their heart. It's not something that you work to earn. It's not anything that you ever deserve. It's a gift. A gift that, hopefully, keeps on giving.
"With the merciful Thou wilt show Thyself merciful." (Psalm 18:25)
Jesus tells a story in Matthew's Gospel (chapter 16), of a man who owed a sizable debt to a creditor. When the creditor forgives the debt but instead of turning around and doing the same to others in a similar position, the man shows no mercy to those who in turn owe him money. The creditor hears of the unmerciful man's conduct and calls for him. Listen to what he tells the man: "O thou wicked servant, I forgave thee all that debt, because thou desiredst me: Shouldest not thou also have had compassion on thy fellowservant, even as I had pity on thee?" (Matthew 18:32-33, emphasis mine) We see here, that in a practical sense, one of the smallest elements of mercy is forgiveness. The creditor tells the man, much like God would tell us, that he forgave him because he desired him. Only God could say something like that. God wants to extend His mercy and forgiveness to us. All we need to do is make the effort to ask. Forgiveness is essential. It's like the oil that keeps our gears from grinding. There are rules in life that must be enforced. Gravity is a law that shows no mercy to the person who does not abide by its strictures. But God's love, at once more ubiquitous than gravity, and also stronger, brings with it the help and mercy and forgiveness needed when anyone (everyone) runs afoul of the things that God requires to appropriate it. And even if you don't feel that you can ask for His mercy, look beyond that feeling which says that you've messed up too much (impossible) and tell God you need His mercy and forgiveness. "Please" and "thank You" work wonders with God, too.
"It is of the Lord's mercies that we are not consumed, because His compassions fail not. They are new every morning: great is Thy faithfulness." (Lamentations 3:22-23)
But again, there's another side to it. Earlier on in Matthew's Gospel (chapter 6), Jesus says "But if ye forgive not men their trespasses, neither will your Father forgive your trespasses." We are all blind in certain areas. Only God sees all, and only God has the wisdom and wherewithal to know why those blind spots exist. Whenever we humble ourselves and admit that we don't know everything, either about ourselves or about others, we put ourselves in a position to receive the mercy and forgiveness that we will inevitably need. So forgive the person who cut you off in traffic, who cussed you out, who glared at you and unsettled the rest of your afternoon. This hardly needs restating, but who knows what caused them to act that way? To act in such an antisocial manner? God knows. And by humbling yourself in each incident, you have the high ground. Your simple act of mercy and forgiveness can be the first fissure that eventually leads to the cracking and crumbling of their facade to the world. That's when God can begin to deal with that person.
Because if you're the only person who sees how someone truly is, then you're the person who God will hold responsible for seeing His mercy and His forgiveness applied to their life.
"And mercy rejoiceth against judgment" (James 2:13)