Answer:
Step-by-step explanation:
The most precise revision of the sentence could be: "If we cannot see the humor in the changing, serious world around us, we are at risk of internalizing the harsh realities of life, which can be damaging to us mentally as well as physically." This revision clarifies that the risk of internalizing the harsh realities of life is related to not being able to see the humor in the world, and it also specifies that the potential damage is both mental and physical.