Vigorous vs. moderate/light

In the exercises it has options for vigorous or moderate for most of them. Can someone explain how they define what is vigorous and what is lighter? To me if I do x amount of time of let's say aerobics, I'm going to put vigorous because I'm fat and it's hard to do lol. I'm sure that's not right ough so can someone else tell me how they classify their efforts in the two options?

You would most likely be overestimating your level of effort. Those descriptors are going to assume you're in relatively good condition and thus truly exerting yourself to that level. Simply being untrained does not raise your actual level of exertion...it just means you're untrained and out of shape.

Vigorous is described under the assumption that you are an athlete trained to push to the absolute limit, not simply that it is difficult for you to do. I'd put down light/moderate simply because it's safer and more accurate to overestimate what you eat and underestimate what you burn. If you want a little more accuracy for how many calories you burn during a workout, you can get a heart rate monitor.

I think I would go with Mayo clinic since they're using the heart rate method to determine how vigorously you're exercising. Early on, your heart rate will increase dramatically over moderate exercise. Don't think you should go harder/faster so that you're doing vigorous exercise - you'll kill yourself. Vigorous to you is determined by you and your athleticism, not by what everyone else's degree of fitness is. How vigorously you exercise will increase the more you do it. If I'm burning it up on the treadmill going as fast as I can and huffing and puffing, trust me, I'm going to say I'm exercising vigorously although Usain Bolt would likely disagree.

I think I would go with Mayo clinic since they're using the heart rate method to determine how vigorously you're exercising. Early on, your heart rate will increase dramatically over moderate exercise. Don't think you should go harder/faster so that you're doing vigorous exercise - you'll kill yourself. Vigorous to you is determined by you and your athleticism, not by what everyone else's degree of fitness is. How vigorously you exercise will increase the more you do it. If I'm burning it up on the treadmill going as fast as I can and huffing and puffing, trust me, I'm going to say I'm exercising vigorously although Usain Bolt would likely disagree.

The problem with this thinking is that, all else being equal, if you're untrained and unfit and go for a three mile run, your HR will be more elevated than a trained individual at the same level of effort...but, again, everything else being equal you're going to burn roughly the same amount of calories for your effort.

Your HR isn't directly correlated with calorie burn...and for individuals who are out of shape...or individuals who have a higher than normal resting HR (resulting in higher than normal working HRs) will have inflated calorie burns using a HRM.

A 3 mile moderately paced run is a 3 mile moderately paced run regardless of whether you are trained or not.

I think I would go with Mayo clinic since they're using the heart rate method to determine how vigorously you're exercising. Early on, your heart rate will increase dramatically over moderate exercise. Don't think you should go harder/faster so that you're doing vigorous exercise - you'll kill yourself. Vigorous to you is determined by you and your athleticism, not by what everyone else's degree of fitness is. How vigorously you exercise will increase the more you do it. If I'm burning it up on the treadmill going as fast as I can and huffing and puffing, trust me, I'm going to say I'm exercising vigorously although Usain Bolt would likely disagree.

The problem with this thinking is that, all else being equal, if you're untrained and unfit and go for a three mile run, your HR will be more elevated than a trained individual at the same level of effort...but, again, everything else being equal you're going to burn roughly the same amount of calories for your effort.

Your HR isn't directly correlated with calorie burn...and for individuals who are out of shape...or individuals who have a higher than normal resting HR (resulting in higher than normal working HRs) will have inflated calorie burns using a HRM.

A 3 mile moderately paced run is a 3 mile moderately paced run regardless of whether you are trained or not.

I think, for all us amateurs around here, you nailed it with just one word: effort.
For a variety of reasons, I use a heart rate monitor when I train. And when I'm pushing the top 2 heart rate zones, then for me, the workout was VIGOROUS! I'm coughing up a lung or 2, and I don't really care much about classifications after that...lol
Granted, with progress in training, the same performance will probably result in a much lower heart rate and less calories burnt in the future. Then I will just make another effort to keep up the burn!

Train safe!