The Greek ekkakeō (also spelled enkakeō) means to lose heart, grow weary, or give up — specifically in the face of difficulty or discouragement. Paul uses it repeatedly in his letters as a warning against spiritual fatigue: 'do not lose heart' in prayer (Luke 18:1), in ministry (2 Corinthians 4:1, 16; 4:16), in doing good (Galatians 6:9; 2 Thessalonians 3:13), and in intercessory prayer for the Ephesians (Ephesians 3:13).
Ekkakeō is the enemy of faithful endurance. Paul's most repeated pastoral command may be 'do not ekkakeō' — addressed to himself and to every church he led. The temptation to give up in ministry, prayer, and perseverance is real and perennial. But God's mercies sustain (2 Corinthians 4:1 — 'since through God's mercy we have this ministry, we do not lose heart'). Galatians 6:9 ties the promise directly to the warning: 'Let us not become weary in doing good, for at the proper time we will reap a harvest if we do not give up.'