The notes are all quarter notes until "lengthen," which is sung to a half note and a quarter note. The increased note value of that half note gives a sense of that "lengthen[ing]." It's also illustrated simply in the syllable count of the words: in this line, "shadows" and "lengthen" are the only words with more than one syllable.
Writing about those features also gives me the opportunity to note something I realized about two years ago but didn't consider significant enough to write about on its own. Later in the third verse are the lines "I know that You will strengthen / My steps toward home. / Then nothing can impede me." Impede is related to the Latin word for foot (pes), so there's something of a link back to the "steps" in the previous line. (Note, however, that since the text is translated, this may be specific to the English.)
