What does it mean that morning willpower is highest?

Your willpower is typically strongest early in the day — schedule demanding tasks accordingly.

Example: You have a quarterly strategy document to write and forty emails to answer. If you open your inbox at 8 AM, you spend your highest-capacity hours parsing other people's priorities, making dozens of small reply decisions, and absorbing the emotional texture of complaints, requests, and ambiguities. By 10:30 AM, when you finally open the blank document, you feel drained and the sentences will not come. Reverse the order. Write the strategy document from 8 to 10 AM, when your self-regulatory capacity is at its peak. Process email from 10:30 to noon, when you still have adequate capacity but no longer need the full force of creative deliberation. The same two tasks, the same total hours, but the output quality of the strategy document is categorically better because you matched the task to the resource curve instead of letting your inbox dictate your cognitive schedule.

Try this: For one week, track two things each hour of your workday: what you worked on, and a subjective rating from 1 to 5 of how much self-control and focus you felt you had available. At the end of the week, plot your average willpower rating by hour. You will almost certainly see a peak in the first two to three hours after waking, a dip after lunch, and a modest recovery in the late afternoon. Now compare this curve against what you actually spent those hours doing. Identify the single most demanding cognitive task in your current workload and reschedule it into your peak window for the following week. Note the difference in output quality and subjective effort.