This tutorial invites a sincere observation of our efforts. Circumstances within us and outside of us continually change. So must our efforts. With each change, a new key must be found to a new lock. The mind (intellectual center) is responsible for finding the key, the heart (emotional center) for generating the force behind its usage.
Can you observe moments in which your mind knows the right effort, but your heart lacks the desire to make that effort? Can you observe moments in which your heart has the desire to make an effort, but your mind cannot find the right key? And can you observe moments where heart and mind unite, resulting in a higher state?