Note that in the last stanza, the speaker says he took the road less traveled by, indicating that he took a path most would not have taken. Many have interpreted this poem in this way but many scholars claim that this is a misinterpretation. Keep in mind that the speaker says this with a "sigh":
I shall be telling this with a sigh
Somewhere ages and ages hence:
Two roads diverged in a wood, and I--
I took the one less traveled by,
And that has made all the difference.
Clearly, the road he chose has made all the difference in his life. And the speaker wonders where the road not taken would have led him. But note in the second stanza that the roads looked the same: ". . . the passing there / Had worn them really about the same." The roads looked the same. This is why the speaker, in the last stanza, says with a "sigh" that he took the road less traveled by. He took one road of two that looked the same; therefore neither road looked less traveled. While wondering about what the road not taken would have been like, the speaker is essentially trying to convince himself that he took the more special road, the road less traveled by. In other words, with that "sigh" he tries to put his mind at ease, telling himself/the reader that he took the less traveled, more difficult road. The fact is that he made a choice between two options that looked equally intriguing. In the end, he wonders about the road not taken and he muses to himself that he took the more interesting path.