With the "unschedule," you create a chart of your entire (24-hour) day, filling it in with all the things you do on a regular basis, such as eating, sleeping, commuting, and chores, and then you add in your appointments like meetings and medical visits. Then you specifically schedule in good stuff, like free time, leisure reading, time with friends, recreation, etc. The author advises to leave at least one day per week for recreation and for any "small" chores. Once you've created your "unschedule," then you only add in "work" AFTER you have completed at least 30 minutes of uninterrupted work. You can use the unschedule for various purposes. One is to make sure you have scheduled enough "guilt-free play" in your week. In theory, you will be able to settle down to work when you know you have some fun things planned. You can also look back over your week to see how much quality work you actually got done, thus focusing on the positive instead of on what you didn't get done. Reviewing it will also give you an overall awareness of your work patterns, such as helping you identify your most productive time of day to work.
There are a number of tools that are part of the author's strategy for "overcoming procrastination and enjoying guilt-free play." I read the book recently and am finding it a challenge to apply all the tools. I think it is helpful to focus on one chapter or tool for the week or the month and start with that.