"The waves of the mind can be made to flow in two opposite directions - either toward the objective world ("the will to desire") or toward true self-knowledge ("the will to liberation"). Therefore both practice and non-attachment are necessary. Indeed, it is useless and potentially even dangerous to attempt one without the other. If we attempt to practice spiritual disciplines without attempting to control the thought-waves of desire, our minds will become violently agitated and perhaps permanently unbalanced.""Practice is the repeated effort to follow the disciplines which give permanent control of the thought-waves of the mind."
"Practice becomes firmly grounded when it has been cultivated for a long time, uninterruptedly, with earnest devotion."
"Non-attachment is self-mastery; it is freedom from desire for what is seen or heard."
-- Patanjali's Yoga Sutras: 13-15 --
"If we attempt nothing more than a rigid negative control of the waves of desire, without raising waves of love, compassion and devotion to oppose them then the result may be even more tragic. This is why certain puritans suddenly and mysteriously commit suicide. They make a cold, stern effort to be "good" - that is, not to think "bad thoughts" - and when they fail, as human beings sometimes must, they cannot face this humiliation, which is really nothing but hurt pride, and the emptiness inside themselves. In the Taoist scriptures we read: "Heaven arms with compassion those whom it would not see destroyed."
. . .
"Perseverance is very important in this connection. No temporary failure, however disgraceful or humiliating, should ever be used as an excuse for giving up the struggle. . . . No failure is ever really a failure unless we stop trying altogether - indeed, it may be a blessing in disguise, a much needed lesson."
[Isherwood and Prabhavananda, "How to Know God," pp. 28-29.]
In the attached video, spiritual teacher Paramahamsa Nithyananda discusses the importance of practice in Patanjali's yoga sutras (above), highlighting the dangers that may arise when the spiritual aspirant employs spiritual techniques in practice without a true understanding of how and why such techniques are used.
In terms of practice being "cultivated for a long time, uninterruptedly," Nithyananda stresses that this is not in sole reference to linear time, but is rather a recognition that, like the Buddha, the aspirant must realize and determine that 'practice' is a life-long commitment that must be continuously cultivated. The dedication of the spiritual aspirant must, therefore, be to the practice of 'being enlightened' rather than to that of 'seeking enlightenment.' In the end, even the desire to 'become' enlightened - like all other desires - must be dropped, says Nithyananda.