Meditation is the way to concentrate inside or connect internally to forget about the outside world. Once meditator practice it , it gives outstanding result and after continuously practicing sometime meditator will be connected to the supreme soul ,Who is source of abundant energy . The experience of each Meditator may be different but one thing is common that after regularly doing the meditation , The Meditator will feel peace and calm As you know the yog asana is necessary for our body to keep it healthy , in the same way Meditation is necessary for soul to keep it happy and peaceful. As we regularly adapt this practice of meditation , It helps us to save us from certain disease like hypertension , depression, anger ,anxiety etc After this it is concluded that to upgrade the mental as well as physical level of life, Meditation is very essential to be adapted in daily routine of life
Rajyog is very ancient science through which one can attain or reach to supreme soul .Although this science is very secretive and only few people know it and practiser of this is very rare . Rajyog in vedic astrology is different meaning and as per astrology ,the combination of certain planet in once birth chart create rajyoga and that person attain luxury life just like king but this Rajyoga is different from it and there is no concern of it from mentalistic pleasure.
In Geeta , During preached to Arjun The lord Krishna describe it in below sholak.
राजविद्या राजगुह्यं पवित्रमिदमुत्तमम् | प्रत्यक्षावगमं धर्म्यं सुसुखं कर्तुमव्ययम् || 2||
The Supreme Lord said: O Arjun, because you are not envious of Me, I shall now impart to you this very confidential knowledge and wisdom, upon knowing which you will be released from the miseries of material existence.
Asana is the part of Yog .Our ancient saint realize to maintain healthy body to perform meditation for a longer time,They discovered different form of pose from animal ,birds ,nature and other non living things and categories the same according to their benefit They performed different yoga asana according to body need which protect their body from disease and activated energy flow in the body . In the Yoga Epic Gerenda Samhita there is a total of 84 Asana are discussed out of 32 Asanas are most useful and effective. Which is used in different Sadhana practices for the different purpose.