The process of desensitization is an important part of Exposure
Therapy. Clients often report that they are “exposed” to stressful
situations and events all the time, but that their anxiety has never
improved. Exposure to thoughts and images that make us anxious, done
in an unplanned way, is a random and inefficient process. This is
because focusing on distressing thoughts is something we usually
avoid, so that under normal circumstances the mind actually works
against itself to resist the very process that would ultimately
produce maximum relief.  We may be driven to summon up emotionally
distressing material in an attempt to extinguish it, but then we run
into a counterbalancing desire to avoid it. As a result, our mind
vacillates and the healing process is drawn out. Thus over the course
of many months, the actual exposure is likely to be brief and
sporadic, even though we may feel as if our mind is constantly on the
problem.

Desensitization involves the following: exposing yourself to your
fears in carefully controlled doses, in a systematic way, with the
exposure rate (time and place) controlled entirely by you, so that the
fears eventually lose their ability to upset you. During the process
you need to experience that fear without distracting yourself or
pulling yourself back from it, until that emotion begins to subside.
If you summon up an emotion, and do this over and over, in the absence
of any adverse consequences, as would be the case during a
desensitizing session in a therapist’s office, or if you are at home
just thinking or imagining the situation, it is only a matter of time
before your response to it lessens. This fact is so well established
that it is virtually one of the laws of psychology.