We have kept the most difficult one for the last. Intentionally blank yourself out. Do not think of anything for a minute. Completely block out everything from your mind. This may prove to be extremely tough in the beginning, but don't give up. Keep working on it and gradually increase the time period to five minutes and from there to ten and so on. There is only one principle to this exercise, your mind should be completely free, and not even a single thought should invade your mind. The time of the day, where you are, what you are doing, what you have to do etc. are all thoughts that tend to barge into our mind when we try to blank out. But resist such thoughts by gaining mastery over your thought process.

Please refer to the book for more details on this activity.