As a beginner you will most likely see improvements in your motor skills in the shape of better exercise form within the first two weeks. As you continue to exercise consistently through the next six weeks, you will make considerable strength gains due to various changes in motor unit recruitment, known as neural adaptation.
Although these changes have no cosmetic impact, they are an important stage leading to further progress. After these initial eight weeks or so, you are generally at the intermediate level with everyone else that works out regularly. At this point your body stops relying heavily on neural adaptation and starts depending on increased muscular changes in the form of muscle size and structure, known as hypertrophy.
Your potential in muscular size and structure are fundamentally dependent on your genetics, but age, health, training protocol, diet, rest and many other variables in and out of your control play a great role in future changes.
