It is an excercise where an individual engages himself in a mode of consciousness, in order to introspect ones own self, to realise his inner strengths and weaknesses, to attain calm and peace, to relax and rejuvenate, to understand his emotions and feelings, to clearly perceive and concentrate, to develop his mind with the worldly understandings and to dream of what he expects from his life.
It is typically cleaning or formatting of subconscious mind that consists of various stereotypes, ill thoughts, anger, anxieties, rituals, jealousy that often leads to dissatisfaction, various health issues like stress and depression, inability to reach targets, poor relationships and many more. Earlier, this was practiced as numerous religious traditions and beliefs. Meditation often involves an internal effort to self-regulate the mind in some way.
Psychological yoga and Meditation is not just gaining self control or excercising mentally but also a technique to be awaken from inside to achieve inner peace in order to find the right direction of life so that one is fulfilled, happy and contented.