How do I be at my peak concentration during 3 hours of exam?

Dear Friend, 

Let's first understand what is attention and concentration. 

Attention is a quality of the mind. Attention is the deep desire of the mind to understand. Understanding means settling down, becoming quiet.

Attention arises when the mind says that the ripples created by objects in mind must settle down. These objects could be:

1. a TV program
2. two people and their chatter
3. the disquiet of the mind itself

However, remember that there is a difference between attention and concentration. In attention, there is no specific object. Attention is the quality of the mind in which it is alert to everything, including itself. Hence, whatever is in its purview is its object. Alternately, there is no (specific) object. Alternately, the mind itself is its own object.

In concentration, there is a process of ego-based choice involved. Concentration is fragmentary. Concentration is upon a specific object that the ego has chosen for its benefit. Concentration does not give understanding, it only gives pleasure and satisfaction.

Understanding results in a cessation of tension. That is the only ‘feeling’ it gives.
Satisfaction is always motive-driven. If there is satisfaction, there is bound to be the (apparent) fulfillment of some desire.

AJ