The idea of this phase is to let your body settle. Your body will have been given a  big shake up while adjusting to  a new routine, and needs time to settle into it. Changing it all around again will put the body through more stress and increase the likelihood of dropping out. This phase gives your body more time if it is still adjusting, and to get into a proper routine that becomes more natural, rather than it being a struggle. Many people find it difficult to fit a new fitness plan into their daily and weekly lives. This phase allows it to take place, letting you get used to exercising at times that are sustainable within your daily life. Without this, you can soon become tired and worn out, and the thing most likely to go is the exercise.