Which path does the narrator actually take in "The Road Not Taken" by Robert Frost?

The speaker takes the seemingly less traveled road.

The speaker says he came to a fork in the road in the woods, and had to choose between a well-traveled road and one that was not. He chooses the less-traveled road and this made all the difference for him. Many people interpret this to mean you should take risks in life.

The two roads are a metaphor for paths in life. In one path, you do what a majority of people do. In the other path, you do something unique. The speaker cannot really tell which road is more used because both are covered with leaves, so he chooses the one he thinks fewer people take.

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.

The speaker is telling us about the roads years after he made his choice. He took the road few took, and it made a big, presumably positive difference in his life. When you make your own choices, it can be difficult but often very rewarding.

In life, many people take the road less traveled. You could be an inventor, an artist, or a writer. Doing something different than others means there may not be many examples for you to follow and you may face resistance. It can, however, also work out very well for you and the world to which you contribute.

Once he chose a road, the narrator knows the chances of going back and taking the other were slim. Life is kind of like that. Once you make a choice, you never go back to the person you were. You can make another choice later, but it is not the same choice.