Blessed are the merciful: for they shall obtain mercy.
Mercy cannot be a passive virtue: kindly feelings towards someone in distress are worthless if not accompanied by action to help relieve the distress.
There may be a time when we are called upon to perform some major act of mercy, but we should not waste our time searching for such an occasion. Rather look for opportunities to do small acts of mercy every day. In the long run, more good will be done in this way than by standing around waiting to do something big.
Better yet, don’t be too particular about being recognized as the doer of those small acts of mercy. An amazing amount of good can be done if we don’t care who gets the credit for it.
It is true that others are apt to respond kindly to the one who shows kindness but don’t count on it. Don’t be merciful for that reason, rather look on it as storing up treasures in heaven.