Although I am appreciative about this article, I would like to say as below.

It's not only about feeling "if only ..." about acts in past or during time of youth; in real life as we grow if we look back we can always feel "if only ..." about almost each activity of ours. I feel that it is like Back-view Mirror Driving.

My feeling is that we should drive looking through the windshield and avoid wrong paths using our older experiences.