Through meditation on a form of God and through mantra japa, the mind gains one-pointedness.

Elephant holds a chain

 (from  'Who am I?'): 

762 The restless swaying of an elephant's trunk is stilled by [giving it] an iron chain, which it holds comfortably. Likewise, the stealthy movement of the weak and impure mind will cease completely by holding onto a name and form [of God or the Guru].

Bhagavan: Just like pranayama, meditation upon a form of God, repetition of sacred words, mantra japa, and regulation of diet are mere aids for controlling the mind.

Through meditation on a form of God and through mantra japa, the mind gains one-pointedness. Just as when a chain is given to an elephant to hold in its trunk, which is always wandering, that elephant will go along holding the chain instead of trying to catch any other thing, so also when the mind, which is always wandering, is trained to hold any one name or form of God, it will cling only to that.