FrequencyFrequency: how often you work out. You need to be exercising AT LEAST three times a week for there to be any benefit/change to your body
Intensity: how hard you are working out. Some days you should go easy and other days you need to push yourself
Time: how long you work out for. The national recommendation is at least 30 minutes a day
Type: what kind of exercise you are doing. This can be running, biking, hiking, swimming, walking, soccer, etc.
The second is the overload principle. I think this is one of the most important concepts to understand as you are training. The overload principle states that your body responds to the stresses placed on it, and if you want to improve you need to stress your body. So if you run 3 miles every day at the same pace, it is going to become really easy for you. You are also going to stop getting as much benefit from it because your body has adapted to that stress. You need to increase time and/or speed. If you apply it to weight lifting-once a weight and reps set becomes easy, you need to increase the weight or add more reps to each set. You need to keep your body in a constant state of adaptation.
The overload principle and FITT work hand in hand. You need to apply the overload principle to each of the FITT areas. Overload even applies to Type.....e.g. Type could be running and then you can classify it even further into hill running, speed running, recovery running, etc. Apply these principles to your training program and start seeing improvement! Set a goal, choose a race, and as you train, think about these things as you strive to become a faster, stronger, better runner.