What is the difference between exercise and exertion? If the amount of effort, tiredness and mental fortitude required for either is same, then what differentiates between exercise and exertion?

There’s only one answer — Who is driving it?

If you voluntarily make yourself go through pain and hardships towards a goal, then every day is fun and happy because your eyes are set on the goal. If the world is making you go through pain and hardships, then every day is like a slow death.

Exercise builds. Exertion kills.