Samadhi is very difficult to achieve. Very devoted life can achieve this stage, however if God wishes then with Gods blessings one can achieve Samadhi (e.g. in mangrol even the normal persons who had no faith in God achieved Samadhi)
Performing and practising eight-fold Yoga can achieve Samadhi i.e. Ashtang Yoga Sadhna and
2. Niyam - controlling of sense organs and body sense organs
3. Aasan - achieving perfectly the eight four postures of Yoga Asans (positions)
4. Pranayam - control over main forces e.g. breathing.
There are four vital stages:
5. Pratyahar - to control Antahkaran i.e. internal organs e.g. maan, buddhi, chitt, ahamkar. All these should be controlled and brought back from all the worldly objects. They should control fully and not partially.
6. Dharan - all eternal organs should be controlled and concentrated in the centre of the heart and to stay there firmly
7. Dhyan - learn and accept and experience difference between Atma (soul) and Body. One should feel that he is Atma and not the body. When he feels that he is Atma, during this feeling he sees the Lord Supreme in divine human form then he has achieved dhyan.
8. Samadhi - when he has controlled all the above seven he loses his consciousness and sees Lord Supreme at this point he is in samadhi. His heart stops throbbing and pulse stops beating as if the body is dead and he does not feel anything through the body i.e. he will not come out of samadhi even if his body is cut or scorched with fire.
Addressing Muktanand Swami he said "I am giving you the power to enter others into Samadhi, so that you can show them Akshardham and Lord Supreme. You can also show them numerous universes, the creation and the destruction."