What do the last two lines of the poem, "I took the one less traveled by, and that has made all the difference," suggest?

This is one of the most frequently asked question and very
important.

First let us consider the previous line
-

I shall be
telling with a
sigh

The
"sigh" in this line has confused every person on Earth who has read this as it can be a
sigh of relief or a sigh of a depressed individual. However, this commonly taken as a
sigh of relief, which will easily answer your
question.

Frost took the path less trodden
upon, the uncommon path. He was one of those individuals who dared to
dare. Now, "ages and ages hence" he says that he "took the one less travelled by, and
that has made all the difference" .

This clearly shows that
Frost advocates the message of courage and risk-taking. He tells us that
there will often be two choices in our life - one, the common one and two, the uncommon
one.

He took the uncommon one
which is brought him unbound fame, wealth and a sigh of
relief.

For your interest, you may wonder
how can we deduce whether it is a sigh of relief. Once, he had said
-

It was
aprivate jest at the expense of those who thought I was sad of the way I was leading my
life.