"The Air of Mars" (1970) by Dmitri Bilenkin. Its only English publication was in The Air of Mars and Other Stories of Time and Space (1976) edited (and translated) by Mirra Ginsburg.
A young man or youth, because of some accident or misfortune, (perhaps his vehicle crashed) is stranded alone and forced to try to walk to safety.
He walked across the cold, red plain for two days and two nights--forward, only forward. He wore a clearly visible bright blue space suit, but he did not delude himself with the hope that he would be found by his comrades. It would be a sheer miracle if the hum of a motor broke into the monotonous howl of Martian air.
It is part of the story that he is not as strong as most people; not that he is disabled, just that he is not as strong or as fast.
The other boys treated him with tolerant condescension, as a weakling, and the gym teachers detested him. The doctors had diagnosed the boy as "healthy." He had a normal body and normal limbs. What right had he to frustrate and humiliate them, hanging on the rope like a sack of potatoes? Gym classes were the nightmare of Severgin's childhood and adolescence.
The end of the story:
He jumped up. And was breathless. As though a mask were pressed against his lips. Yet still he went on. His lungs rose and fell, faster, faster. They were convulsing with pain. A rattle came from his constricted throat. He dropped down to his knees but still crawled forward. And when his mind turned blank and his body thrashed about in agony, he tore off his helmet and gulped the Martian wind as a drowning man gulps water, because he cannot help but gulp it.
A chill passed through his lungs, a last intolerable flash of pain, and everything went black.
Everything went black, only to start glimmering again. He came to slowly from the convulsions that had seemed to tear his lungs apart and saw something wavering and red before his eyes.
With an incredible effort he raised his head. It was already light. And he was crawling! He was breathing Martian air! His organism was different from others—he survived!
He did not even realize this. He did not think. He continued to crawl, fiercely, stubbornly, no longer obeying reason, but moved by pure instinct, on and on, toward the place where there were people.