Patanjali details the 6th limb of ashtang yoga,
Deshabandhashchittasya dhaaranaa ॥01॥
Chittasya: of mind
Dharna is the state when mind is focussed at one place or thought.
Having mastered the five senses and being no longer their slave, the practitioner is able to achieve the state of one-pointed focus, the object of focus being prescribed by the Guru. This is the state of dharna. Our body is programmed to achieve whatever it wants, provided it is one thing. Words like ekagrata, ek tatva nirantar abhyas, bhumadhya, all indicate that the path to success is one-pointed focus.