1. I am generally not exceeding my AT even though I followed the mathematical formula. Does it mean I possibly have a lower AT? 2. Is being close to the AT a problem or anything below is truly safe? Sometimes I feel very exhausted but my numbers aren't in the range but feel like I am overdoing it. 3. How do we get our hearts healthy if we are always aiming to be below cardio levels and AT? What good is exercising aside from strength if we can't build our hearts?