The Bible records that David, the shepherd boy chose not to wear the armor of a soldier, that King Saul armed him with, when he averred to fight the giant, Goliath (1 Samuel 17:38-39). But David did wear another kind of armor, an armor that was more effective than the physical armor that he chose not to wear, against an armored foe. It was a spiritual armor that He wore.

The Bible records that when David faced Goliath, he RAN towards the army of the Philistines (1 Samuel 17:48) and downed him with a stone from his slingshot. The Bible also records that once Goliath fell with his face to the ground, David RAN again to slay and behead the giant Goliath. Revelation 6:4 informs us that war takes away peace and when Goliath the Philistine warrior,  stole the peace of the Israelites by defying them and the Lord who was their Captain (1 Samuel 18:51), David’s feet ran with readiness to restore peace. To run is indicative of readiness; readiness to engage in battle.

Our feet must be fitted with readiness of the gospel of peace, as was David’s. When the giants of this world (pleasure, prosperity, power, popularity, etc) deny and defy Christ Jesus, the Lord of Peace, we must run and engage with readiness to restore the Peace of the gospel in their heart.

1 Samuel 17:48, 51 (KJV)
48
And it came to pass, when the Philistine arose, and came, and drew nigh to meet David, that David hastened, and ran toward the army to meet the Philistine.
51
Therefore David ran, and stood upon the Philistine, and took his sword, and drew it out of the sheath thereof, and slew him, and cut off his head therewith. And when the Philistines saw their champion was dead, they fled.

Ephesians 6:15 (KJV)
15 And your feet shod with the preparation of the gospel of peace;