Consciousness
The purpose of existence itself is a question, and it is question-related to consciousness. The relationship between the physical components of the brain and the subjective, particular experiences people have as a result of them has been poorly understood by many specialists throughout history, from ancient philosophers to contemporary neuroscientists.
One of philosophy's and science's greatest mysteries is consciousness, which has the potential to provide answers to some of humanity's most complex medical issues, including the aforementioned neurodegenerative diseases. Even if there is a physical component to consciousness, people still don't fully understand which parts of the brain are in charge of it. Patients with extensive spinal cord injuries are known to still be conscious and have some type of worldly experience despite having nearly no remaining brain function and senses.
Early in the morning, you may notice that the Sun is just beginning to rise, hear a few birds tweeting, and perhaps even experience a brief moment of joy as the cool morning air touches your face. In other words, you are conscious.