When designing an aerobic or strength training exercise program, fitness professionals, such as personal trainers and gym instructors, invariably use the F.I.T.T. principle as their starting point. The good news is that with a little bit of knowledge anyone can use this principle in designing an exercise program that will help them to become progressively fitter and stronger, and help them lose or control their weight.

If you want to start an exercise program or take your current routine to the next level, you