Matthew 5:5

Blessed (inwardly peaceful, spiritually secure, worthy of respect) are the gentle (the kind-hearted, the sweet-spirited, the self-controlled), for they will inherit the earth.  

If we have a close relationship with God and the word of God, the easier it is to have inward peace.  The God kind of inward peace trusts and relies on God for direction and can react to any circumstance in peace.  Self-control is vital with God because we are not responding with our feelings or the flesh.