What this means is, when you consider doing any kind of workout in the gym, there are several variables that you need to consider to make it the right one for you. For example, when you're going to do cardio exercise, you'll ask yourself, "How often should I get on that treadmill in order to lose 18 pounds of body fat within 8 weeks for my competition?" You'll also ask, "Will I take my heart rate to within the 80-90% max range, or stay within the 50-75% Heart rate range?"  You'll, of course, set a time, such as "I'll do 20 minutes in the morning on an empty stomach, and then 30 minutes in the evening after my last meal." And when you've had enough of the treadmill or are thinking you aren't getting enough out of it and your body has come to expect it, you'll say, "Is it time to get on another type of equipment? Or should I go outside and run or walk stairs or just jog?" And with all of these decisions, you'll likely have to experiment with all of this. Not only will you respond differently to all of the things you try, but your body will constantly change, too, so you'll always have to revamp your decisions in the F.I.T.T. category!  You can also apply F.I.T.T. to workouts and make decisions in the same manner.  See, now you know almost everything about F.I.T.T. and you're an expert - now go forth and prosper in the gym!