In order to be effective, fitness training must be well assimilated and personalized. The process of learning and mastering the exercises properly takes a lot of time. Many of the movements must be practiced until they become automatisms; this way, the focus will be on the muscles that are worked out and on intensity of practice, rather than on the execution technique. But this routine of training has also some disadvantages.
One of them is monotony – the exercises get to be really boring for the practitioners. On the other hand, at least 4-6 weeks are necessary for checking and proving the potential of training, developing, losing weight, etc. that a program might have. A shorter period of time will not be enough for drawing relevant conclusions on the effectiveness of the program. Thus, a certain psychological resistance to monotony is necessary from the very beginning.
Another disadvantage of routine is the fact that the muscles act under the principle of economy of effort. This means that, soon after starting the program, they do not react to the stimulus with the same effectiveness as in the beginning. A state of limitation intervenes, when, in spite of the same efforts, the sportsman will not progress any more. Stagnation of good results might be very frustrating for the sportsman, who could, finally, abandon training completely. For avoiding this, it is advisable to change the program periodically, so that the muscles will have time to 'forget' the first exercises; the sportsman can come back to them after getting through a few different programs.
A completely new program can have disadvantages, for example the fact that learning it demands an increased effort of attention, of focusing, and sometimes even involve mental stress, determined by the degree of difficulty of the program. However, some practitioners can see a positive aspect in this, considering the new program as a challenge, which will 'refresh' them psychologically.

On the other hand, a too frequent change of programs can be as ineffective as maintaining them for too long. Changing the program before benefiting of all its potential of progress is like giving up antibiotics treatment after you have the impression that the symptoms disappeared.
It is important for the sportsman to observe carefully his own reactions from one training to the next; this way he will be able to choose the best moment for taking up new routine. It is very easy to consider some temporary states of indisposition, irritability or tiredness as limitation or overtraining and to abandon, in consequence, a program which would still have a lot to offer.
This is another case in which the experience accumulated by the practitioner in months or years of training will help him take the right decision and change the program when it is best for the body. If the sportsman makes the right choice, he will feel progress even in the first sessions of training and he will not need a long period of adaptation.
In time, the sportsman can develop a conditioned reflex, meaning that the body will ask regularly, at certain intervals, for a change in the routine of the training. This way, new solutions can be anticipated for getting over the critical fazes of stagnation. Moreover, the interest for the training will remain constant.

The active breaks (active recovery), which must be initiated once a trimester, a semester or a year, can submit to this rhythmic conditioning. They intrinsically belong to the training and their importance must not be underestimated.