Exercise // Thinker: How Hard Should I Exercise?
Why are you asking this question?
You might want to ensure that your exercise is as effective as it can be. Maybe it's a safety concern. Perhaps you are getting conflicting advice from (allegedly) credible sources.
Or, all of the above.
Sorry to exaggerate your frustration: what is your goal?
Furthermore, does "hard" even need to enter into the equation right now?