Step one: You can't be trained in God's army until you belong to it. That means you have to pass over from death unto life by faith in the atonement made for you by Jesus Christ, and His resurrection from the dead. I mean, any Commander in Chief would be foolish to train soldiers of an opposing army.
Step two: You must realize that you are in a war, a spiritual war. This is the step that usually creates a problem with immature Christians. They are saved, but they don't know they are in a war. Until they realize this they can't be trained. Becoming aware of this spiritual war and opening your whole being to God, makes you trainable. You'll make mistakes, but God isn't worried so much about the mistakes. You are, after all, in training.
Step three: You must be trained. This again becomes an obstacle to many because even though they are aware that a war is going on all around them, they allow fear or sin or whatever to keep them on the sidelines. Once they surrender to God, then He is able to train them. Each warrior of God has one very special talent, and that is the ability to allow God's power flow through them. How this is manifested is up to the Holy Spirit and the circumstances of that particular battle. So God trains us. He puts us in situations where we will have to reach beyond ourselves and trust Him. For in Him we find our true power and strength. (This is nicely brought out in Some Have Entertained Angels by the way)
Step four: You have to enter battle. Now don't be deceived. Even battles are part of our training, but training for something beyond when we will just be warriors. The Bible gives us glimpses of what we will be doing in Heaven, and it's not sitting at the table eating, or bowing down and praising God, or playing harps, although (minus the harps) those things will be part of our experience. The apostle Paul tells us that we will judge angels, and in another place that we will govern nations. Understand, at that time we will have a new immortal body, that is perfect and holy. One that is not limited by time and space. So we will be able to do all this things, and more, all at the same time. So we are being trained, fashioned, to become like Christ in the most ultimate of ways possible without actually becoming Christ Himself, so that we, like Him, and in Him, can enjoy our rest, oversee peace, administer justice and righteousness. These are things we should be learning to do now. We may fail, but there will come a day when all this training comes to bear and we will not fail, nor shall we glory in ourselves. We will know fully and completely that we are holy and righteous because of Jesus, and that one thing alone will so fill us with joy that we will be unable to contain us.
The Call: God is looking for people willing to submit so totally to Him that they will not only deny their every selfish desire, but be filled with a zeal to do whatever God asks of them. People who will try and fall down and get back up again. God knows we aren't perfect. That's why He's training us. You see, there is a whole world out there that doesn't know that He loves them. If we can let them know, even in our failures, God will use us.
You'll find elements of each of these steps throughout this wonderful work, and more if you are willing to look for it. I hope you'll pick up a copy today and see some more about the beauty of God that you haven't seen or realized before.