The fifth step of yoga is pratyahara, which literally means "withdrawal." This is the crux of yoga, the lever that lifts the consciousness to the heights of meditation. To master pratyahara, one must first have established the previous four steps of yoga, and then be able to control how the consciousness uses the senses.

“When the mind follows the wandering senses, then it carries away one’s discrimination, as the wind does a ship on the water...” — Krishna, Bhagavad-gita 2:67

"...concentration is the first and foremost thing a sadhaka or aspirant should acquire in the spiritual path." —Swami Sivananda

“When, like the tortoise that withdraws its limbs on all sides, one withdraws the indriya from sense-objects, then consciousness becomes steady.” — Krishna, Bhagavad-gita 2:67