Let's get down and dirty!
There are a few principles of exercise which we should address. The first one is the Principle of Overload. This is a key component. In order to improve one's physical fitness, the muscles must be stressed. You do THIS, by increasing the intensity, or duration, or range of motion.
The second principle, is that of PROGRESSION. This means that overload should be increased graudally, over the course of your fitness program. However, progression that is too slow will result in limited improvement. Progression that is too fast will result in chronic fatigue and injury. Use the 10% rule for increasing your progression. For example, if you are running for 20 minutes, the next week- run 22 minutes.
The third principle is SPECIFICITY. This means that the training is specific to the muscles involved in teh activity. You won't get great arm improvement in a 10 week jogging program.
Last, the Principle of RECUPERATION. the body requires recovery periods between exercise training sessions in order to adapt to the exercise stress. This is essential for maximal benefit from your exercise!
Love you all, and good running, cycling, swimming etc!