Stress, in this poem, is not a mood but a load, "a cart of broken boulders." In six short lines the speaker moves from complaint to bravado, then to a confused confession, and finally to a flat admission of defeat. The central idea is that hiding a struggle can become part of the struggle. The speaker keeps up an act of coping so firmly that the act itself looks like the next stage of the problem.
The opening simile is physical and slightly odd. A cart is something you pull, and it implies a long, grinding journey. "Broken" boulders are more awkward than whole ones, jagged and impossible to pack neatly. The line is long and its stresses fall heavily on "weighed heavy," so the reader feels the slowness. The next line answers with a swagger: "I bet I could carry more on my shoulders." The cart has vanished and the burden has moved onto the body. "I bet" sounds like a dare, or even a gambler's phrase, and the neat rhyme of "boulders" and "shoulders" gives the boast a snap of confidence. The speaker is turning exhaustion into a competition with themselves.
That tidy couplet is the last stretch of order in the poem. The third line sprawls: "The boulders ultimately worthless except for some shiny pieces of gold." It has no verb and reads like an afterthought, as though the speaker is talking themselves into a new view of the burden. The sentence contradicts itself, since something "worthless" is rescued by something valuable inside it. The next line, "To hide the secret that nobody knows," begins with an infinitive that attaches to nothing. Read one way, the rubble exists to hide the gold. Read another, the speaker carries the whole heavy pile in order to hide the secret. The poem never says which, and the ambiguity suits a speaker who is not telling everything. Judging by the imagery, the "gold" may be whatever the speaker most wants to protect, while the stress is the cover story that keeps people from looking closely.
Then comes the sharpest turn: "Relax, I am relaxed!" It is a command and a reply in one line, as if two voices are arguing, or one voice is rehearsing what it wants others to hear. The exclamation mark gives it away, because calm people rarely need to shout about it. The formal "I am" instead of "I'm" adds to the stiffness. Compare how easily the earlier "I bet I could" slid by. The poem has become more rigid at exactly the moment it claims to loosen up.
The last line, "Heading for another relapse," drops the exclamation mark and the "I." There is no subject at all, as if the speaker has stepped outside themselves and is watching the pattern from a distance. "Another" is the most important word here. It tells us this has happened before, so the poem is describing a cycle and not a single bad day. "Relapse" also quietly echoes "relaxed." The two words share a opening sound, and the denial in one line is undone by the near-rhyme in the next. The poem does not say what the speaker is relapsing into, whether a habit, an illness, or a mood, and that restraint keeps it open to many readers' experience.
The title, "Art in Human Behaviour III," is worth a second look. The numeral suggests the poem is one of a sequence, though the text alone does not tell us more. "Art" may point to the performance on display, the skilled artifice of seeming fine. If so, the title treats ordinary concealment as a kind of craft, and the poem as a glimpse behind it.
What makes the poem worth reading is its compression and its honesty about self-deception. It uses very few words and a single image of rubble and gold, and it shows how the rhyme, the rhythm and the confidence all come apart as the speaker gets closer to the truth. It suggests that "I'm fine" can be the heaviest thing a person carries.