A baby shark was put into the same fish tank as a goldfish. Though in the same tank, they were separated by a transparent piece of glass.
Each day, the baby shark would try to eat the goldfish. He would crash into the glass, but failed all attempts to reach the goldfish.
Some months later, the owner removed the glass.
The baby shark remained at his portion of the fish tank, leaving the goldfish unscathed.
Why so?
Cos he had went through pain in all his attempts to reach the goldfish. He gave up finally, fearing to go through the pain again. He would rather be timely fed by the owner, wont go hungry anyway.