Yoga Sutras of Patanjali translated by Yogi Kalinath - Chapter 3, Verse 24
Pada 3, Sutra 24
By constraint on strengths, one acquires the strength of an elephant
What ever strength constraint the Yogi focuses on, he will attain. It is possible to stimulate the vital force within by exclusively focusing on extraordinary strength such as that of an elephant.
By persistent practice of this Samyama (constraint) together with external strengthening exercises it is possible to develop extraordinary physical strength.
Consciousness is the seed and essence of all strengths. When consciousness becomes absorbed in and has communion with an object in nature such as an animal or an element (e.g. wind), one absorbs the qualities of that animal or element.