You decide that since your parents sometimes treat you like a child sometimes, you decide to make yourself mentally 5, with clothes that but to make things more interesting you set the settings so the world knows that you arent really 5.
Ok, if I do this right the only person who will think I am 5 is myself.
You set the settings and fire at yourself. You begin to shrink and your clothes change as you shrink. While this is happening your mind simply starts to fade, your memories of being older vanish, your education vanish, your thoughs of stuff you like vanish, your wisdom of right and wrong also vanish.
After a minute of transformation, you are 100% a 5 yr old, you have no knowledge or memory of being older, you have clothes on that fit and everyone knows you arent 5 and probably be shocked when they see you like this but you wouldnt notice since you now think you have always been this young.
Why am I down here? I should be playing with my toys.
You go upstairs to find your..... and they get a shock of their lives.