Ephesians 6:18 through all prayer and petition, praying at all times in the Spirit, and watching to this same thing with all perseverance and petition concerning all the saints.
I'm sure many a non-praying soldier changed his mind and started praying as he went into battle. For the Christian soldier prayer is indispensable. The Christian is fighting forces he cannot see. He is fighting forces stronger than himself. Prayer is his only hope of winning a battle against such forces. It doesn't matter how well armed the person is, without prayer, without God, the battle will be lost.
Prayer is how we keep the lines of communication open between us and God. Our relationship with God helps us see the truth, shows us the righteousness we have in Christ. A relationship with God gives us peace of mind, helps us hang on to our faith, reminds us of our hope in salvation and helps us hear the Spirit remind us of texts when we need them. Prayer also opens our minds so the Spirit can help us understand what we read in the Bible.
Prayer is not part of the armor listed. Once the Christian is armed with the tools for battle, he now prays before entering battle. Therefore the armor is how we live all day long, but we don't start the day without prayer. We are to pray at all times. This is not something to do once in a while. In everything we do we should be aware of our need for God and staying in tune with Him. We should be asking God to stay with us and guide us in our every word, thought and action. Prayer is what holds the armor together and God is who fights our battles for us. The armor is our protection, but God is the one who can see and fight the forces that we cannot see or fight.
The Christian watches for opportunities to pray also for others. He's persistent in his petitions to God for others. He doesn't become discouraged or give up. Nothing pulls people together more than to be praying for each other. We're more accepting and forgiving of each other when we're praying for each other. Just as troops work together to win a war, so should Christians pray together and for each other to fight the Christian battle. There is no need for us to ever enter into battle alone. We have God fighting for us and we have each other to offer support and encouragement to one another.