The reference answer is as follows:
The "mountain" in "standing in front is the mountain" refers to countless difficulties and obstacles, figuratively speaking.
The "mountain" in "Stepping on the foot is also a mountain" refers to the realistic mountain. This sentence ignores the previous metaphor, which means that the mountain in front and the mountain at the foot are mountains. Since I set foot on the mountain, I am still afraid of the mountain in front of me. Just go ahead bravely. The mountain in front of you, like the mountain under your feet, means encouragement. So there is the following sentence: "Only my eyes are gone, but my feet are always awake".
Or the answer: the "mountain" in "stepping on the foot is also a mountain" refers to the difficulties that have been overcome.
I hope I have not misled you.