How do I treat rest as part of the practice?

You want rest to be part of the practice rather than a gap in it. Start by noticing where the belief came from. Effort is visible and rest is not, so effort gets counted and rest gets tolerated. But steadiness is the aim, and steadiness is not built by effort alone. Practice needs both the applied effort and the letting go. Only one of those is in your calendar. First, put rest where you can see it. An unscheduled rest is not rest; it is the absence of a plan, and it fills with scrolling. Give it a time and a shape. Second, distinguish rest from collapse. Collapse is what happens when you postpone rest until the body takes it by force. Rest chosen in advance restores you. Rest taken under duress mostly repairs damage. They feel entirely different afterwards. Third, notice the guilt without obeying it. The guilt will arrive on schedule. It is a habit, not information. You can rest while feeling you should not, and the feeling gets quieter each time you do not act on it. Fourth, watch what returns when you rest properly — patience, attention, the willingness to begin. Those are the practice. When did you last rest before you needed to?