What does Mark 8:3 mean?

Sometime before, Jesus and His disciples had practically fled the crowds of Capernaum (Mark 4:35–36) and retreated to the eastern shore of the Sea of Galilee (Mark 5:1). Immediately, they were met by a man possessed by a legion of demons. Jesus agreed not to send the demons into the abyss, and the demons offered to leave the man and enter a herd of pigs, instead. The pigs promptly rushed down the hill into the sea and drowned.
The people of the region begged Jesus to leave: whether in fear of His power or in defense of their livestock we don't know. The freed man begged to stay with Jesus. Jesus told him, instead, to return to his friends and tell them how God had saved him (Mark 5:1–20). The man clearly did so: Upon Jesus' next visit, He is swarmed with a crowd from throughout Decapolis who have spent three days receiving healing and glorifying God (Matthew 15:29–31).

Now they are healed, but hungry. "Faint" comes from the Greek root word ekluo. It means to weaken or exhaust one's strength. The people who had once feared for their livelihood now willingly leave it behind to receive Jesus' blessings. This is the power of a Christian testimony. The four Gospels are stories of Jesus' time on earth, and we are also called to tell the story of Jesus' love for us. Our tale doesn't have to be as dramatic as release from demon possession. But Jesus has worked in every believer, and the people of the world needs those stories of hope before they exhaust their strength in this life.