After outlining a day of a student explaining what he needs to worship and recite, the author repeated some important pieces of advice. The advice here is specifically directed at anyone who is not in the workplace or business.
One who is not engaged by job or business should focus on worshiping only. He can pray Sunnah prayers and then recite Quran. He can also remember Allah by his heart. He should not spend time in negligence. His surrounding always distract him from Allah and his remembrance. Many thoughts flashes trough his mind and he starts talking to himself. This eventually take him to far away from Allah and hereafter.
It is difficult to engage always in Salat and recitation. When one becomes idle, he thinks about something that triggers him to a lot of events and people. So, he needs to observe his thoughts and feelings.
The author blames self-talk and says that it leads to hardness of the heart, because generally self-talk is about worldly affairs and matters. In the next chapter, he guides how to turn inhale and exhale in to Ibadah. Meaning his slef-talk eventually turns into thoughts about Allah and the hereafter.