Me, I'd not change anything about my past, for fear of mucking up my present.
I've had experiences, some good, some bad, and made decisions both good and bad. They're all valuable. They all made me what I am today.
In some ways, the bad decisions we make are more
important than the good ones.
Think of this. Every time you've made a bad decision, you've likely looked back on it, and perhaps thought "wow, that was a bad decision... I'll not do that
again!". You've just learned something, and in recognizing is as something undesirable, eliminate it from your future -- from all
Replacing all your "bad" decisions with good ones might not allow you to ever gain that sense of perspective -- you won't have learned from your mistakes, and your chance of committing them in the future will go up significantly.
Often, the mistakes we've made in the past have greater consequenses should we commit them in the future.
Bad experiences too (whether the result of our decisions or not), shape us similarly.
Also, (because I enjoy telling stories) let me relate a little Chinese parable I once heard regarding this:
One day, a poor farmer was in his home, avoiding the heat of the day and drinking tea, when his wife came running through the door, obviously distressed.
"What is the matter, wife?" said the farmer.
"Your best horse has just run off! What will we do? We can't possibly afford another! We are ruined!" cried his wife, wringing her skirt with her hands.
The farmer, though concerned, continued to drink his tea. "Don't fear, wife, how do we know this isn't a blessing in disguise?"
The farmer resumed his work and did not worry upon the issue further.
Sure enough, the very next day, the horse returned to the farm, bringing with him a mare. After a time, the mare had a colt, which grew to be an even more magnificent steed than his sire -- whom the farmer's son loved so much, that the farmer gave him the young steed as a gift.
One day, while the farmer's son was out riding the young steed, it caught sight of a fox, panicked, and threw the farmer's son, breaking both his legs. Another local farmer had seen the accident, and rushed to the aid of the son.
When the son was returned home, the village doctor set the bones, but declared that the boy would forever be crippled, and would need to walk with the aid of a crutch for the rest of his life.
The farmer's wife was distraught. "How could this happen to us?! Our only son, a cripple!"
The farmer, though saddened, comforted his wife. "Fear not, wife." he said, "Our son is alive! Anyway, how do we not know this is a blessing in disguise?"
A month later, as the farmer's son was hobbling about the grounds on his crutch, an official messenger bearing the governor's seal rode by on his horse.
"You there, cripple! Are there any able-bodied young men at your house? All homes in this province must deliver their able sons to the army for training. War is upon us!"
The farmer's son mentioned he, in fact, was the only son of his father. The messenger, eyeing the boy leaning heavily on his crutch, replied: "Well, no matter then. There are other households I must visit this day!" and rode off toward the next farm.
One year later, it was reported that the province's army had been annhilated by the enemy. Not a single one of the village's sons would be returning... alive.
Save the farmer's crippled son. Unable to walk properly, he had dedicated himself to the study of literature and politics. In time, he was recognized for his scholarly achievements, and was appointed governor of a large and wealthy region, where he lived out his days to great satisfaction. Bringing his parents with him, they lived in great comfort to the end of their days.
Of course, knowing the past changes a bit... but still, you only know of one past -- the one you've experienced yourself. Messing with the past is like trading your current life for one that may be much better, or may be much worse than the one you've got.
I, who am quite pleased with my present, am unwilling to take that gamble.
However, my future is always a concern, and there's much to be done about that! So I look to what I can accomplish and how I can ensure my future is at least as pleasant and rewarding as my present.