Normally we are very selective in our view of ourselves.  When we look into a mirror we are careful to strike the most flattering pose, the most pleasing expression.  In the same way we each have a mental image of ourselves which emphasizes admirable qualities, minimizes defects, and omits some sides of our character altogether. [...] Instead of a carefully edited self-image, the meditator confronts the whole uncensored truth.  Certain aspects of it are bound to be hard to accept.

At times it may seem that instead of finding inner peace one has found nothing but agitation by meditating.  Another surprise, however, is that the difficulties pass away. 

Cutting open the lesion and pressing on it to remove the pus is painful, but unless this is done the wound can never heal.
The Art of Living: Vipassana Meditation as taught by SN Goenka, page 7