As per Great Sage Patanjali (Patanjali Yoga Sutra 2:29) there are eight limbs of yoga. They are yama, niyama, asana, pranayama pratyahara, dharana, dhyana and samadhi.
Ahinsha, (Non-killing), Stya( truthfulness), Astya(non-stealing), Brahmcharya (continence), and Aparigraha (non-receiving), are called Yama or Self restrain.
To develop this virtue one must start with Non-killing or loving-kindness. Once you start practicing loving-kindness in thoughts, words, and in action you can practice non killing or non violence more easily. If you develop oneness with GOD or Parbrahm or Christ consciousness whatever name you can give to THAT supreme power and oneness with all, you will be Ahinshak- non-killer or nonviolent of your own without any special effort. To develop virtue of non-killing or oneness with all or any other limb of yoga you must need determination and enthusiasm. These both are very necessary to reach at ultimate goal of self realization. With very careful self observation and with enthusiasm you must keep developing one yama(virtue) at time or all at time according to your own spiritual growth and mind power. But in all the most important thing is to keep your ultimate goal in your mind otherwise with personal development you will get some power or Siddhi and if you are not very careful about your ultimate goal, you will lost in that power or siddhi.
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