We reign in life in being conformed to the image of God's firstborn Son through the Spirit's interceding that all things may work together for the conformation of those who love God (Rom. 8:26-29).
We reign in life in being glorified (v. 30) to be redeemed in our body (v. 23c) to participate in our divine sonship ultimately (v. 23b) through the sealing of the indwelling Spirit (Eph. 4:30).
When we reign in life, we more than conquer the environmental hardships and sufferings by having God being for us, who did not spare His own Son, who gives us freely all things with Him, and who has chosen us and justified us (Rom. 8:31-33); by having Christ who died for us, who was raised, and who is sitting at the right hand of God interceding for us (v. 34); by being captivated by the love of Christ and by the love of God in Christ from which we are inseparable (vv. 35-39); and by being faithful to Christ and God unto death (v. 38).
When we receive the abundance of grace and of the gift of righteousness to reign in life, we gain the righteousness of God which is the subjective Christ (9:18-33; Phil. 3:9; 1 Cor. 1:30). This righteousness is gained out of faith to faith (Rom. 1:17a) according to His mercy in order to make known the riches of His glory upon vessels of mercy (9:18-23).
When we reign in life, we enjoy the riches of God (10:12-15) by calling on the name of the Lord (v. 13), by believing in the Lord's word (v. 14), and by announcing the glad tidings (v. 15). It is only when we reign in life that we can call on the Lord properly.