The change is necessary and important. This change is the power of Rudra, the Transformer. The change should be progressive in nature. The change shall not cause any disturbing feeling.
The practice of yoga is to bring citta balanced; to control the fluctuating thought waves of the mind by modifying them.
Yama, niyama, asana, pranayama and prathyahara are the practices of Hatha Yoga.
Raja Yoga is also called the yoga of meditation. In meditation, the mind will be inside the body focussing on the internal objects, like, the breath, the heart, etc.