I really liked how he started chapter 4 by saying that prayer is the central function of our life of faith, and it is the very heartbeat of our life in God. Therefore our prayer life will certainly become a target for Satan.
I sometimes struggle with prayer because it is not always something easy to do and my mind gets easily distracted on other tasks that have to be completed. I then beat myself up for not being focused in prayer. I like the way Hallesby says that our carnal mind will mobilize all the reasons for us not to pray now. I need to decide to pray first and to enter into the Spirit of prayer. To do that, I can come to Jesus with my helpless self and ask him to bring me into the spirit of prayer to commune with him.