In "The Road Not Taken," we see a man with a decision to make. He has come to a fork in the road and must decide which road to take. In the first stanza of the poem, we see the regret that he faces.
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;
We see that the regret that he faces is that he could not travel both roads. He goes on to say that in the future he might come back and take the other road, but he knows that is unlikely to happen.
At some point in our lives we all face this same dilemma. We all come to a place in life where we have to make a choice about whether we will follow one path or take another one. This poem talks about this same thing. We must choose a path to take, and when we look back on it, we might have some regrets about not taking the other path. We will question ourselves about where the other path would have led us, but in the end, all the paths will eventually lead us to the same place. Each path may have different experiences on it, but it will lead us to where we need to be. This is probably Frost's most famous poem. It is an example of how we question ourselves and our decisions, and how we have to decide on a certain road and take it.