The title borrows the language of an old medical remedy, the idea that a sick person might be sent out of doors to breathe their way back to health. The ailment in these eight lines, though, is not a disease. It is work, and a particular kind: "all the dull work that may kill." The speaker's trouble is that he does it "dully." The adverb repeats the adjective, so the dullness is both in the task and in the person doing it, and each feeds the other. That loop is the problem the poem sets out to break.
The cure, such as it is, is a walk. "I am going into the country" is the poem's one plain declaration of action, and it arrives in the present progressive, as though the speaker is already on his way and not merely planning to go. What follows bends the sentence out of shape: "the old marl of knowing." Marl is a crumbly, lime-rich clay, the kind of earth that was traditionally dug up and spread to improve poor soil. Calling knowledge "marl" turns it into something physical, an old ground you can stand on or dig into. The phrase can be read as a description of the country itself, or as a second place the speaker is heading, deeper in. With no punctuation to settle it, both readings stay open. The countryside here is not a scenic backdrop. It is dirt, and that is part of why it feels trustworthy.
The next couplet turns that earthy knowledge toward the body: "how I ought to walk / to be repaired." Two small words carry a lot. "Ought" brings in obligation, as if there is a correct way to walk, one the speaker has forgotten or never practised. "Repaired" treats him like a tool or a pair of boots, something worn down that can be mended. It also carries an older sense of the verb, to repair to a place, meaning to go there. Whether or not the poet intended that second meaning, it fits a poem about travelling in order to be fixed.
The ending is the most telling part: "with any humor / with any other time." The speaker no longer asks for a good mood, only for "any" humor, and "any" other time. The word shows how low his expectations have fallen, and how little he is bargaining for. "Humor" can mean amusement, but it can also mean a person's disposition, in the old sense of a temperament that can sour or sweeten. "Any other time" suggests a time unlike the work-hours that have been wearing him out, a slower or looser kind of time. The repeated "with" also leaves it unclear whether humor and time are what he walks with, what repairs him, or both. The poem stops without a full stop, so the request hangs there unanswered.
Formally, the poem is four unrhymed couplets with no punctuation. Its sound-patterning is quiet but real. "Dull," "do" and "dully" cluster hard on the d, so the opening sounds as plodding as the work it describes. "Kill" echoes the l of "dull" and "dully." Later, "old," "of" and "knowing" share a rounded vowel, and in many accents "ought" and "walk" nearly rhyme. The first couplet drops from a seven-syllable line to a four-syllable one, as if the speaker is deflating mid-thought. After that the lines are short and level, close to the pace of steps. The verbs also change as the poem goes on, from "do" to "going" to "walk," so it moves from labour to movement even though nothing is resolved.
Modal words carry the uncertainty: work that "may" kill, a way of walking he "ought" to know, humor of "any" sort. Nothing is guaranteed, and that restraint is what makes the poem persuasive. It does not claim that nature heals. It suggests that a person worn down by dull work might begin to recover by changing the pace and the kind of time he lives in, and that a bit of mud underfoot and a few minutes of different time might be enough to start.
That is where its significance lies. In under thirty words it describes a modern kind of exhaustion without self-pity and offers a modest hope in place of a grand one. Judging by this poem alone, it trusts plain words and open syntax to leave a reader room to wonder what their own "other time" might be.