The size of your bucket determines how much water you can draw from the well. The following words were spoken by our Lord to St. Maria Faustina of the Most Blessed Sacrament:
"The graces of My mercy are drawn by means of one vessel only, and that is -- trust. The more a soul trusts, the more it will receive." (Diary 1578)
As we trust, Jesus fills us with His mercy, even to overflowing. What can we do but pass it on to others.
"When a soul approaches Me with trust, I fill it with such an abundance of graces that it cannot contain them within itself, but radiates them to other souls." (Diary 1074)