Its a placebo, it'll only work if you tell yourself its real.
For instance, you go to a doctor when you are sick, if the doctor gives you 12 pills that are completely useless and do nothing, (its say just a powder put into pill form) and he tells you it'll feel better, chances are your brain will tell your body you feel better just because the doctor said it'll work.
Note; not for actual sicknesses, I mean little stupid stuff.