The feet (which are seperate objects from the body) are procedurally animated in script, making them move perfectly with the player speed and follow the ground slope more naturally. I think that detail makes the hiking more compelling.

I use a coroutine that alternativly calculate the next goal position for the current moving foot. The next goal is just a raycast offseted in the forward vector of the character, this raycast hit the ground and return the next goal position.

For the feet to raise in the air, I use an animation curve to affect the y position of the foot.

All that is multiplied by the player speed so when he's not moving, the feet don't move and don't raise and when the player moves, the height at which the feet raise and the feet goal distance is relative to the player speed.