The first Reiki level mainly focuses on self-treatment. You take the first steps in truly getting to know yourself and developing your personal consciousness.
You engage with your own body and your own behavior in society. This helps you understand the connections between body and mind and learn to perceive the messages of your body.
After all, it's no coincidence that people say "I'm fed up" or "I can't tolerate it anymore". This leads you into conscious targeted self-reflection and, through self-treatment, triggers your self-healing powers.
