Journaling can be enlightening and helpful at this time. Taking time to walk in nature, meditate, or just sit and stare. Tuning into the energies of your body. Try a meditation on the chakras.
At some point prior to your class, either three days prior or even longer, perhaps a week or more, you should begin to prepare your physical essence for the Reiki attunement you will be receiving.
This attunement will clear your energy channels (chakras), and directly and permanently connect you to the source of Universal life force energy, that which we call Reiki.
You can help to create a powerful experience for yourself by preparing your physical be-ing for this attunement. This type of preparation is very common to engage in prior to receiving any type of energy or enlightenment. Native Americans, for example, fast while going on a Vision Quest. Mikao Usui, the founder of Reiki, fasted for 21 days prior to receiving the Reiki energy.
You do NOT have to fast, but eating light and healthy foods a few days or even a week prior will definitely help you to prepare fully.
Avoid substances which will dull and stagnate your internal energy, such as processed foods, sugar, caffeine, alcohol, chocolate, and meat. (If you must have meat, try to limit to fish. It holds a higher vibration).
Think of this not as something you are giving UP for this short time but something you are giving TO yourself.
Reiki is an amazing gift and to receive it fully is joyous.
Keep in mind we are all human and just do the best you can. Either way, Reiki is coming to you! You have chosen it. Congrats.