Sri Krishna suggests a less rigorous practice for those who cannot fix their mind and buddhi on God alone: "If you are unable to fix your mind steadily on Me, O Dhananjaya, then seek to reach Me by the yoga of constant practice." (Bhagavad Gita, 12.9)
An untrained mind is restless, always in a state of flux, wandering from one thing to another. It looks outward, and is ever eager to attach itself to sense objects. Long, steadfast practice is needed to discipline such a mind and give it an inward, Godward turn. Sri Krishna describes this practice in the Gita (6.25-6): "Renouncing entirely all the desires born of the will, withdrawing the senses from every direction by strength of mind, let a man attain tranquility little by little with the help of the buddhi armed with fortitude. Once the mind is established in the Self, he should not think of anything else. Let him withdraw the fickle and unquiet mind from whatever causes it to wander away, and restore it to the control of the Self alone." In other words, practice involves repeatedly bringing the mind back to the object of meditation within.
Arjuna's power of concentration and skill in archery were legendary. He, too, found it difficult to tame his mind. He complains to Sri Krishna: "This yoga, which You, O Madhusudana, have declared to be characterized by evenness–I do not see how it can long endure, because of the restlessness of the mind. For the mind, O Krishna, is restless, turbulent, powerful, and obstinate. To control it is as hard, it seems to me, as to control the wind. (6.33-4) Sri Krishna concedes that "the mind is restless and hard to control," but says that "it can be restrained by practice and by detachment." (6.35) Detachment involves giving up anything that deflects us from the path to God-realization.
When someone said to Sri Ramakrishna that it was extremely difficult to proceed toward God while leading the life of a householder, the Great Master spoke encouragingly: "What about the yoga of practice? At Kamarpukur I have seen the women of the carpenter families selling flattened rice. Let me tell you how alert they are while doing their business. The pestle of the husking-machine that flattens the paddy constantly falls into the hole of the mortar. The woman turns the paddy in the hole with one hand and with the other holds her baby on her lap as she nurses it. In the meantime customers arrive. The machine goes on pounding the paddy, and she carries on her bargains with the customers. She says to them, 'Pay the few pennies you owe me before you take anything more.' You see, she has all these things to do at the same time–nurse the baby, turn the paddy as the pestle pounds it, take the flattened rice out of the hole, and talk to the buyers. This is called the yoga of practice. Fifteen parts of her mind out of sixteen are fixed on the pestle of the husking-machine, lest it should pound her hand. With only one part of her mind she nurses the baby and talks to the buyers. Likewise, he who leads the life of a householder should devote fifteen parts of his mind to God; otherwise he will face ruin and fall into the clutches of Death. He should perform the duties of the world with only one part of his mind."