The title of this poem may be the key to its interpretation. The title is not, as it is often mistaken to be, "The Road Less Traveled," but is "The Road Not Taken." If the title were "The Road Less Traveled," the poem would have a stranger focus on nonconformity – taking the path that others don't take. But the title "The Road Not Taken" focuses the poem on lost opportunities – the road that the speaker did not take.
The poem shows considerable ambivalence about which road is less traveled – one moment, one is more grassy, the next, they're both equally covered with fresh leaves. It seems that, on this autumn morning, neither road looked worn, regardless of what the speaker may say when he tells the story years from now.
But the speaker made a choice, and took a path. In taking that path, he gave up his chance to take the other one. Metaphorically, this means that the speaker is reflecting on his life choices, and how they are going to affect his life. What could have happened if he made a different choice? What his life would have been like?
More than anything in the text of the poem, this title hints that the poem is about lost opportunities, and the complexities of choices, not just choosing the path that is fresh and new.