There are two types of personal historians: Those who chronicle their past with positive accounts of success, support and security; and those who unfortunately have negative recollections that repeatedly return to haunt them, or their history prompts them to want to redo their life.

Interestingly, the difference of the two types is not determined by their experiences.

Our brains record our story. The various sensations of our lives come into the body from all over and are assigned often by feeling to this shelf or that file or some other box for later retrieval and replay.

Reminiscences are constructed from fleeting flashes not concrete. To rerun our memoirs, all the impressions of our past are reactivated from their different individual cubbyholes or sheltered bunkers.

Because the long-ago is rebuilt from scratch every time, it is vulnerable to errors. It can be wrong. If it can be remade it begs the question, what is real?

As clever as the brain is, it misses details, skips the obvious or inserts whole new so-called facts. What we consider to be truth is in fact an amalgamation of billions of brain sparks filtered by moods. The fluidity of the recall mechanism and the resembling process prevents the complete stability and precision of memory.

It is very critical for suffers of past pain to realize that all memories are not permanent.

That is not to say that bad things didn't happen or that the emotional scars don't exist. It is saying our perception of the past is more important than the past itself. It is the perception, more than the events, that is open to renewed interpretation.

It is true we cannot take back abuse or neglect. It is impossible to undo the slights, loses, disappointments, but the heartaches themselves are merely neurological remnants. They no longer exist. Time swept them away. The past is over. It's gone. We don't possess it. We remake it.

Our brains, however, when wounded, recycle the fear. This rehearsal is intended to prepare the person for the next time. However, the endless repeats also force us to relive the sorrow or stress. For the depressed, this reciting and rehashing of negative thoughts is a common symptom. The rumination of the painful is like a cow chewing on the cud of bad-tasting hay.

We human non-cows re-taste a regrettable meal when we regurgitate the bad taste. We literally get heartburn as we reflux the chronic built-up acids over and over again. Tension stimulates gastric juices. What a great simile: We analogously spit up foul memories over and over again in our minds.

Fortunately there are ways to neutralize the acid and relieve the burps.

Philip Zimbardo and John Boyd in The Time Paradox tell us some of the ways we can reconstruct our perception of the past.

The visualization of time gone-by is seen through the emotional glasses we have put on today. Most interesting is that we have the power of reshaping feelings about the past with created lenses of today.

Gratitude is the power game changer. It remakes the feelings of the past. If our brain is filled with gratitude it will be less tolerant of negative thoughts. Gratitude forces us to focus on the positive. It demands our time and our attention. Today's thoughts of appreciation limit the retrieval of regrets and do-overs.

For example these psychologists suggested writing down significant negative events from our past. Then consider the positive lessons we can learn from them. Lastly note how to apply these lessons to the future.

For example sorrowful memories of an early parental death redrawn become a lesson of renewed engagement. Loneliness becomes phone calls to grown children; pity converts to trips to the zoo with grandkids. Regrets turn into new appreciation; insecurity transforms into discovered confidence.

We are captains of our destiny. We start by being historians of our past.

Joseph Cramer, M.D., is a fellow of the American Academy of Pediatrics, practicing pediatrician for more than 25 years and an adjunct professor of pediatrics at the University of Utah. He can be reached at jgcramermd@yahoo.com.