In one of his letters (Epist. 2:1-2,4-5,7: PL edit. [845,] 879, 881), St. Ambrose of Milan writes:
There is a stream which flows down on God's saints like a torrent. There is a rushing river giving joy to the heart that is at peace and makes for peace. Whoever has received from the fullness of this river, like John the Evangelist, like Peter and Paul, lifts up his voice. Just as the apostles lifted up their voices and preached the Gospel throughout the world, so those who drink these waters begin to preach the good news of the Lord Jesus.
May this dreary winter day (at least here in northern Virginia) be one in which you drink from the river and lift up your own voice to preach.