The best method for melting ice is to pour hot water over it. It is the method that is fastest because it puts the ice into such a dramatically opposed environment that it is compelled to melt at an amplified speed. Ice does not care about whether or not it melts. It can be ice, or water, or it can become air if it evaporates.
Ice is ice only if we want it to be ice. It is we who control its state of existence, and it is we who can determine the speed and velocity at which it melts. If I am sipping a warm drink, I might want it to melt quickly in order to cool the drink. However, if I am making homemade ice cream, I might pour salt over the ice to cause it to melt more slowly.
In the context of our relationship with God, he often sees the need to have our hearts melt as fast as possible, while we are inclined to pour on the salt and seek to maintain the status quo for as long as possible. We want to hold out because we believe that one state of existence is preferable over the other. We think that ice is a safer mode of existence.
We fail to recognize that one mode of existence prevails over another only to the extent that different modes have different reasons for being. A disciple of Jesus whose heart remains as ice is unusable by God, unless he chooses instead to have a melted heart, unless he chooses a transformation that comports with his mission and his purpose for being.