Feng Lun took everyone hiking, and saw Wang Shi walking with a limp. When asked, it was because his shoes rubbed his feet.

Feng Lun showed his entrepreneurial demeanor by taking out his own insoles from his shoes and handing them to Wang Shi. Once Wang Shi put them in, he indeed walked more comfortably, and his feet didn't hurt anymore.
After descending the mountain and returning home, Feng Lun forgot about this matter.
Two years later, Wang Shi called Feng Lun and said, "Bro, I’m still using the high-tech insoles you gave me, but they’re no longer soft, they’ve become hard."
Feng Lun replied: "Brother Wang, I bought those sanitary pads at a convenience store before the hike."
Emergency hiking tip: I thought you would just toss them after descending, but why are you still keeping them?"