Hi popmynutsy.
have you gone nuts? Are you sure you are okay? 
Generally human only uses 8~10% of our brains. And we use right
brain more, for logical thinking part.
As for your case, 3%, I highly suggest that the person is suffering
from mental retardation.
Estein, the scientist, used 15% of his brain and was considered a
genius.
Do you know brainwaves help our cells, tissues, bones to develop?
The muscles to move, the nerves all need to use our brains? However
that may only requires 2~3% in your whole life. (Another words, in
your whole life, you only move around without thinking.)
As for memory, if our brain is fully utilized, it will definately
more than giga, more likely archieving Terabtyes or even more. As
there were one case the researcher found from a dead man, he only
uses 1% of his memory and had around 10Gb or information. (Be it
how to move fingers to geography, etc)
Physic power is not neccessary utilizing 100% of your brain. Some
people (even those with 3%, I don't know who 
) are able to wield physic power too.
Most likely physic power is due to the nerves connection of your
brain and the structure of it. When some nerves are connected at
the wrong place, it has addition bio electromotive force created,
this force in small amount can make out body moves, but in a large
amount, it have have telekinesis effect, or physic power.
As for anyone using 100% of his brain, he can't live up to age of
25, his brain will become as rotten as a 120 years old by the age
of 10.
Cheers.
