Imagine getting a second chance to make things right.

A thirtyish man wakes up one morning and discovers he's in his preteen body, but he has all his adult memories intact. Stunned at first, he soon realizes he's been given a chance to undo the many things he regretted. To act on those opportunities he missed. What personal tragedies would he act to prevent? Given this alternate science-fictional universe, what might he change about his life--and the world?