It's totally normal to be a little sore when you're just starting to work out. But as you progress, you need to pay attention to the way in which your body is reacting to what you're doing. If you do 20 lunges after not having done them for awhile, you will be sore the next day - that's how you know the lunges worked those dormant muscles, just as you intended. If you keep doing 20 lunges every day, after a while you will stop feeling the soreness, and that means the move is not productive anymore. It's important to keep yourself challenged in order to get results.

When it comes to intensity, you will learn to use your own judgement. If your effort feels too easy, it probably is. Stop slacking and increase the intensity!! If it feels too difficult or your form is compromised, decrease the intensity. You will find your abilities change as you move forward. If you stop seeing the number on the scale drop, chances are you are coasting on your workout. REV it up!