As with all of the gifts, they are dispensed within the confines of the life of faith. Such individuals are more aware of God than man, and of heaven than the world. They have an appetite for the Word of God, and a desire to minister to God's people. Apostles had a heart for apostleship. Prophets had a heart to prophecy.
Elders have a heart for shepherding.
This is the manner of God's kingdom. Jesus came to save us because He wanted to. Paul ministered to the Gentiles because he desired to do so. Elders feed the flock of God because they want to. They are always for the betterment of Christ's people.