James 1:14-15 But each person is tempted when he is lured and enticed by his own desire. Then desire when it has conceived gives birth to sin, and sin when it is fully grown brings forth death.
Now most of you would say, "duh" to the fact that the more you focus on one thing the less you will focus on other things. Yet you realize it so much more when you actually experience it. In the past few weeks I have been realizing the importance of focusing on Christ continually. The more I focused on my work and the problems in my life the less I focused on Christ and the more frustrated and depressed I became. Yet the more I focused on God, his grace, his forgiveness, and heavenly things the more I became happy I was alive and thankful for the small things in life. Focusing on Christ continually will leave little time for other things to dominate your thoughts. James makes this very clear in the above passage. He points out the importance of focusing on Christ by showing you the opposite affect. The more you focus on the things of this world and of sinful desires the more likely you will be to act on those thoughts and desires. How do 100% of all sins start? With a thought, that thought carries into a desire then finally into action.
Hebrews 3:1 Therefore, holy brothers and sisters, who share in the heavenly calling, fix your thoughts on Jesus, whom we acknowledge as our apostle and high priest.
Now what would happen in you focused all your thoughts on Christ and heavenly things? I think its safe to assume you would be less likely to think of things of this world. This is what James is trying to say. He is trying to show you that the thoughts of man will direct his path. The devil is always trying to plant evil thoughts in our minds to cause us to sin, however; God gives us the strength to fight those thoughts. If you are continually keeping your mind on Christ and heavenly things your perspective will likely change on many parts of your life. Since thoughts direct your actions with your thoughts on Christ you will begin to put into action things God would want you to do. Prayer ties into this. Praying causes us to focus not on ourselves but on Christ. This focus will cause us to think on things of God and hopefully spurn us onto following God more in whatever form that may come in. So in your prayer life a great thing to pray for is for God to give you the strength to fight evil thoughts and help you focus on things of God.