PE Scale

I found this Perceived Exertion scale, and it's pretty good. It's easy to categorize how you feel while you're exercising.

• Level 1: I'm watching TV and eating bon bons
  
• Level 2: I'm comfortable and could maintain this pace all day long
  
• Level 3: I'm still comfortable, but am breathing a bit harder
  
• Level 4: I'm sweating a little, but feel good and can carry on a conversation effortlessly
  
• Level 5: I'm just above comfortable, am sweating more and can still talk easily
  
• Level 6: I can still talk, but am slightly breathless
  
• Level 7: I can still talk, but I don't really want to. I'm sweating like a pig
  
• Level 8: I can grunt in response to your questions and can only keep this pace for a short time period
  
• Level 9: I am probably going to die
  
• Level 10: I am dead