The purpose of yoga is to minimize all obstacles to meditation and thus bring the intelligence to full, vibrant life

The second Chapter of Patanjali’s Yoga Sutras - Sadhana Pada - About the Practice 

Verse 1

तपः स्वाध्यायेश्वरप्रणिधानानि क्रियायोगः ॥१॥

tapaḥ svādhyāy-eśvarapraṇidhānāni kriyā-yogaḥ ॥1॥

Austerity, study of scared literature and surrendering fruits of work to God are called Kriya-Yoga (Yoga in the form of action).

Verse 2.2

समाधिभावनार्थः क्लेश तनूकरणार्थश्च ॥२॥

samādhi-bhāvana-arthaḥ kleśa tanū-karaṇa-arthaś-ca ॥2॥

(It is for) the practice of Samadhi and minimize obstacles.

For Patanjali's, the practice of yoga is the 'yoga of action', kriya-yoga composed of tapas, self-discipline, svadhyaya, self-study and lSvara pranidhana, surrender to God.

Tapas is the blazing desire to burn away the impurities of body, senses and mind.

Svadhyaya is the repetition of sacred mantras and the study of spiritual texts in order to comprehend one's own self.

 lsvara pranidhana is surrender of one's body, mind and soul to lord through love for Him.

By reducing pains to a minimum or even destroying them. 

kriya-yoga promotes profound meditation, which is a prior to samadhi. 

The purpose of this yoga is to minimize all obstacles to meditation and thus bring the intelligence to full, vibrant life.

PATANJALI YOGA SUTRAS