The air's pretty thin. Some can't take it. I think you'll have to go back to Earth.
Benjamin had been living on Mars for quite a while after passing out. The nurses were sorry to inform him that he could not stay on Mars longer due to the poor amount of oxygen and the way his body reacted to it.
Determined to stay, Benjamin decides to plant trees to bring more oxygen into Mars so that he does not have to leave. After over a month of patience and care for the trees, no tree had sprouted. After a couple hours, it starts to rain hard on the plants.
Benjamin woke up to all of the trees he had planted, being as tall as men. Trees, flowers, and bushes of all sorts had been grown in a matter of hours due to the rain that occurred the night before.