Heart or Mind?

One needs to be tamed before it escapes,
It twists you around and leaves you blind.
It mixes up reality with a fantasy world,
It stops time when hours need to go faster.
But it lets you live and it lets you fly,
It lets you do things you never thought you could.
It tell you never to give up,
It always finds a way to make sure you keep going.
Sometimes when you don't expect it,
It tries to replace sense.

The other one gives you doubts,
It makes you aware of all the haters.
It makes you wonder if you can do it,
Sometimes it shuts every door.
It turns you into a self doubter,
It makes you struggle to decide left or right.
It helps you tame yourself,
It tries to calm you down.
Sometimes when you don't expect it,
It tries to replace sensibility.

One is tame while the other is wild,
One is game while the other is mild.
One is left while the other is right,
But you need both of them :  both day and night..