This is going to get abstract.
There is a philosophical concept called “qualia” that states that the subjective experience of something is different than knowing all of the objective facts about it. The taste of a strawberry, that tart sweet flavor, is something you can’t understand without tasting it.
Due to the influence of Lord of the Rings, our adventurers often find themselves staring down a unkempt trail through a dense forest. To be a better DM, you should experience a slice of the adventuring life and hike through a forest. Load up your pack (plan ahead, bring more water than you think you need) and drink in the experiences that the world puts before you. How green are the leaves? Listen to the wind whip around trees and how it creates the sound of a river. How close do the deer get before they bound off? Notice that in heavy brush, you cannot see a few dozen yards beyond the trail… you're in ambush territory. Like a sponge, absorb these experiences and connect them to your game.
Even dirt trails that are “well maintained”, can still be tricky. Footing can slip and it requires your constant attention. The energy you expend is far greater than marching on a flat asphalt road. Unless the trail is constantly traveled, there will be hazards. Freshly fallen trees will have to be traversed. Maybe there are stones that make the trail uneven. Think about the difficulty of trying to escort a wagon on your particular path.
If you go up a steep trail, there will be multiple switchbacks as you carve away across the mountain. Rocks will slip, trails will narrow, and dust will kick up.
Notice how your legs ache the next day, how your knees, quads, glutes, and feet all have a different feeling. If it’s dry, everything is covered in a fine layer of dust; you'll only notice it when you hear tiny crushing noises between your teeth. Characters who have lived a sheltered, studious life, will show some wear after a day or two of hiking.
You don't necessarily have to input a game mechanic for all of this (although your experiences can help you build one), the additional description is enough to help the player envision the moment.
As a DM your experiences can help weave the story that you spin, and you should strive to experience as much of the adventuring life as possible. Obviously you can't learn how to cast spells, but with minimal effort you can camp, hike, and learn to use an axe. Be mindful how these direct experiences can enhance your game.