Self-esteem

G!

I stand upon a rock;
It's a big, hard type of
Rock, maybe a granite,
And on a good day it's
The size of four minivans
Lined up two by two and
Wrapped in a bundle.
The top of the rock is
Flat, with enough room
To lie down, pace about
And jog in little circles on.
The sides of the rock are
Smooth and polished, and
Are impossible to climb.
The only way to get on my
Rock is via a rope ladder
Which I can lower and raise
At will, and this way I control
What gets onto my rock, and
What doesn't. When I stand
Upon my rock I can see for
Miles around, and what I see
Are many rocks just like the
One I stand upon, yet most of
Them are vacant at the top.
Some people might think me
Foolish, for standing atop my
Secluded rock, where there's
Only room for myself, but
I believe as firmly as the
Firmness of my rock that
Where I am is a good place,
And I'd like to stay here.

What do you stand on?