Athayoganushasanam: NOW THE DISCIPLINE OF YOGA.
Yoga is discipline. It is an effort on your part to change yourself.
The "NOW" indicates to the state of mind. If you are disillusioned, if you are hopeless, if you have completely become aware of the futility of all desires. If this moment has come, Patanjali says, NOW THE DISCIPLINE OF YOGA. Only now you can understand the science of yoga, the discipline of yoga.
If that moment has not come, you can go on studying yoga, you can become a great scholar, but you will not be a yogi. You can write thesis upon it, you can give discourses upon it, but you will not be a yogi. The moment has not come for you. Intellectually you can become interested, through your mind you can be related to yoga, but yoga is nothing if it is not a discipline.
This "now" may not have come. Then I may go on talking about yoga but you will not listen. You can listen only if the moment is present in you.
Yoga means now you will have to be a harmony, you will have to become one