If you can't take your heart rate, a good way to recognize that you're exercising efficiently is whether or not a. you're experiencing a little bit of huffing and puffing. b. it's difficult to have a conversation. c. you're gasping for breath. d. your muscles are burning.

I most commonly hear that the answer is B. it's difficult to have a conversation. 

The saying goes like this:
If you can sing while you are exercising, you aren't working hard enough.
If you find it hard to sing or can keep up an interrupted conversation, you are working at a good pace.
If you find it hard to breathe, then you are working too hard.

The administration should take action.

Pm me i don't get it