Let's look at some subtle clues in the poem for attitudes and emotions:
"Sorry I could not travel both / And be one traveler" The speaker wants to live his life to the fullest extent, and if he could, he would travel both paths. However, he is realistic about his limitations, and he does not allow these limitations to ruin his experience, instead accepting certain aspects of life.
"Just as fair / And having perhaps the better claim / Because it was grassy and wanted wear" The more attractive prospect is the one that is less used, indicating that the speaker is excited by the idea of adventure and discovery.
"Oh, I kept the first for another day!" The speaker does not disparage people who disagree with him, thereby taking the more commonly used path. He is accepting and tolerates difference.
"Yet knowing how way leads to way / I doubted if I should ever come back" This is not the speaker's first journey, and although he expresses a desire to return and take the other path as well, he is wise and experienced enough to recognize that this may never happen. However, he is willing to sacrifice this path for the infinite paths he has not yet encountered.