वपुः कृशत्वं वदने प्रशन्नता नादस्फुटत्वं नयने सुनिर्मले । 
अरोगता विन्दुजयोऽग्निदीपनं नाडीर्विशुद्धिः हठसिद्धिलक्षणम् ।।

These are the indications of achieving perfection in hatha-yoga: the body becomes slim, the face glows with delight, the inner sound (Nada) manifests, the eyes look serene, perfect health is gained, sense-desire will be under control, digestive fire stay alive, Ida and Pingala nadi will go through purification.

Vapu Krishattvam

Netra Acharya