This lecture continues the explanation of the first chapter of the Yoga Sutras by Patanjali, specifically addressing the chief obstacles to yoga (union), and how to overcome them. The key passage says:

"These are the obstacles [to achieving yoga]: disease, dullness, doubt, carelessness, laziness, intemperance, worldliness or sensuality, mistaken notions due to illusions, missing the point, instability, causing distractions of the mind. Pain, despair, tremor of the body, [irregular] inhalation and exhalation are the companions of the causes of distraction [oscillation of the mind]. To prevent these, [one should have] intense practice on one subject." — Patanjali, Yoga Sutras 1:30-32