"The Road Not Taken" seems to be a bit of a conclusion in life; at the very least, the speaker is at a vantage point in his life where he can reflect upon the different choices that he has made and the affect the choices have had on his life.
The symbolization is the metaphor of "life is a road or path" and it is the speaker's travel upon the rough one, the one that had not been made smooth by frequent travel that has made him who he is ("that has made all the difference").
Often when speaking on this, I make an allusion to "Stopping by the Woods on a Snowy Evening"- also by Robert Frost. My purpose is to show the speaker here could be the speaker in "Road Not Taken" but on an individual life's journey rather the collective one spoke of in "Road". "Woods" shows the speaker doing the unconventional- watching the woods fill up with snow, while he still has miles to go.
If you are not familiar with "Stopping by the Woods", I've included a link.
Frost's classic poem "The Road Not Taken" is one of a handful of poems that are universally discussed and analyzed by readers, teachers, and students.
The message in the poem is clear and inspirational. The speaker considers two paths, and chooses one. The tone is nostalgic for the moment of choice that has long since past, having relished the anticipation of the experience and the contemplation at the place where the roads divided in the woods.
The broader symbolic implications are, of course, for more than a walk in the woods. The poem encourages individuality, confidence, and a no-regrets attitude.
Despite the ambiguity that surrounds the poet’s intent, the poem succeeds. The two roads are aptly symbolic of the choices we have to make almost every day of our lives.
Still, perhaps the poem’s essential playfulness is evident in the dramatic “sigh” with which the speaker expects some day to talk about his choice, and in the portentousness of the last line, which seems a bit exaggerated considering that the two roads were “really about the same.”
This classic poem is so often misunderstood as incorrectly being about a road "less-travelled," that it is often overlooked that the two roads were "just as fair," "worn ...really about the same," and "both equally lay."