The first time I read Frost's poem many years ago, I thought I understood it easily. I take it to be a reflection on a career decision that Frost made some years earlier. Evidently he wanted to write poetry, but he knew that it is difficult if not impossible to make a living writing poetry. It always has been. One of the diverging roads would lead to a lifetime of extreme simplicity and near poverty, similar to the life led by another New Englander, Henry David Thoreau. The other road would have been more practical. It is a road taken by a lot of creative people who want to have comfortable lives and not to be dependent on their creative output for their livelihoods. Typically this road leads into the business world or into academia. But having, in effect, two careers, trying to go down two roads at the same time, can have a negative effect on creativity and can also have a negative effect on the practical career. Frost knew this. He chose to live a simple country life and devote himself to his writinig. Success did not really come to him until he was an old man. His poetry describes the simple life he led on farms in New Hampshire and elsewhere in New England. That was my interpretation of his poem. He seems to think that his soul is immortal and that he will be telling about his career decision after his mortal death.
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.
He is, in fact, still telling us about his dilemma and his final choice some years after his death. The life he chose provided the material for his writing.