Sutra 21
Tivrasamvegaanaamaasannah
Tivra: Fast, quick
Samveganaam: Momentum, intensity
Aasannah: Progress, near, early
Sage Patanjali goes on to detail more sanskaars. The sanskaar to achieve the sanskaars mentioned in previous sutras at a speedy pace.
The burning desire for Yoga should be there 24x7. With every passing second, the body is deteriorating as is its capacity, and the being is moving further away from reality towards destruction. Therefore, a sadhak needs to develop the sanskaar to pursue his sadhna with a steady pace, without any slack.