You decide you want to become a baby but you dont want anyone to freak out seing you as a baby so you write in the notebook:
"I was born in 2003 instead of 1981."
As soon as you wrote it you felt yourself change, first you shrunk and your clothes changed as well, your teeth went away and your hair became lighter and shorter.
Everything in the room changed as well. Your bed changed from a mature person bed to a teen like bed, then pre teen, then child like then a crib. All your stuff turned into baby stuff like toys and lights.
When the transformation is complete you are a baby of 8 months old. But the question is do you have your memory left?