Tradition
St. John Chrysostom
On the Priesthood
Book III › Section 8
8. Do not thus, I pray and beseech you. I know my own soul, how feeble and puny it is: I know the magnitude of this ministry, and the great difficulty of the work; for more stormy billows vex the soul of the priest than the gales which disturb the sea.
Source: On the Priesthood (New Advent)