When the body is cleansed, the mind purified and the senses controlled,joyful awareness needed to realize the inner self, also comes.

Verse 2.41

सत्त्वशुद्धिः सौमनस्यैकाग्र्येन्द्रियजयाअत्मदर्शन योग्यत्वानि च ॥४१॥

sattva-śuddhiḥ saumanasya-ikāgry-endriyajaya-ātmadarśana yogyatvāni ca ॥41॥

When the body is cleansed, the mind purified and the senses controlled,

joyful awareness needed to realize the inner self, also comes.

Verse 2.42

संतोषातनुत्तमस्सुखलाभः ॥४२॥

saṁtoṣāt-anuttamas-sukhalābhaḥ ॥42॥

From contentment and benevolence of consciousness comes supreme happiness

By this practice the Sattva material will prevail, and the mind will become concentrated and cheerful. The first sign that you are become Spiritual is that you are becoming cheerful.

A pleasurable feeling is the nature of the Sattva. Everything is pleasurable to the Sattvika man, and when this comes, know that you are progressing in Yoga. All pain is caused by Tamas, so you must get rid of that; moroseness is one of the results of Tamas. 

The strong, the well-knit, the young, the healthy, the daring alone are fit to be Yogis. To the Yogi everything is bliss, every human face that he sees brings cheerfulness to him.

That is the sign of a virtuous man. Misery is caused by sin, and by no other cause. What business have you with clouded faces; it is terrible. 

If you have a clouded face do not go out that day, shut yourself up in your room. What right have you to carry this disease out into the world? 

When your mind has become controlled you will have control over the whole body; instead of being a slave to the machine, the machine will be your slave. Instead of this machine being able to drag the soul down it will be its greatest helpmate.

Through cleanliness of the body, contentment is achieved. Together they ignite the flame of tapas, propelling the sadhaka towards the fire of knowledge.

This transformation, which indicates that the sadhaka is on the right path of concentration, enables him to look inwards through Self-study

(svadhyaya) and then towards Godliness.

A purely sattwic outlook makes one see only the feel positive in everything. Those people who tell themselves they owe it to—the world? themselves? their growing children? society? their self-respect?—to see the dark side of everything haven’t nearly the impact on everything and everybody that those have whose outlook on life is sattwic and forever cheerful.

All good things, moreover, come from sattwa: sense mastery, concentration, inner communion. All these things follow from having a pure consciousness. One cannot attain true happiness by merely hoping for it, gloomily! One must decide to be happy if he would go beyond contentment and achieve a state of vital, vibrant happiness. Happiness doesnt depend on who you are or what you have, it solely depends on what you think. Think that you are happy, you will eventually be happy. Happiness always instantaneous.

Happiness will elude a man who in spite of having everything in abundance, craves for more. Contentment is the most essential quality for a man. Without this, a man cannot be happy.

PATANJALI YOGA SUTRAS