This is a famous and in my view somewhat misunderstood poem, the misunderstanding being entirely the fault of the poet. Robert Frost liked to put it about that this was a playful poem written to tease his friend Edward Thomas, who was, it seems, given to reflecting ruefully on the choice of path after one of their country walks together and saying now if only they’d gone the other way… In particular the last line, Frost claimed, was an ironic joke at Thomas’s expense and not to be taken literally. Thomas did indeed take the tease seriously and was apparently quite perturbed by the poem, but to me all this was just Frost putting up a smokescreen: clearly the poem is about him and not Thomas, the road less taken is the path of poetry, and there is no reason not to take the last line at face value: our life choices do indeed make a difference. I’m afraid Frost liked to play these games, maybe from a wish to disguise the act of self-revelation, or from a fear of committing himself too deeply to his own truth, or just from a mischievous sense of fun. Which doesn’t make it any less of a fine poem.
The Road Not Taken
Two roads diverged in a yellow wood,
And sorry I could not travel both
And be one traveler, long I stood
And looked down one as far as I could
To where it bent in the undergrowth;
Then took the other, as just as fair,
And having perhaps the better claim,
Because it was grassy and wanted wear;
Though as for that the passing there
Had worn them really about the same,
And both that morning equally lay
In leaves no step had trodden black.
Oh, I kept the first for another day!
Yet knowing how way leads on to way,
I doubted if I should ever come back.
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.
Robert Frost
David Sutton 
Hi David, I think I read the poem a bit differently to you. Surely one of the main points about it is that the road taken is not less travelled (as he recognised at the time) – though many years later when he tells the story he claims it was. So the poem is (in part) about myth making?
I think this apparently cavalier admission as to the possible unreliability of his memory is just part of the smokescreen. Frost was well aware of his liking for playing games with his readers and once famously said in a moment of honesty ‘Check up on me some!’. I mildly deplore this myself, feeling that if poets say a thing the thing should be as they say, but I guess in practice that’s a bit idealistic.