Generally, yoga practice is executed for getting some material profit: aṇimā laghimā prāpti īśitā vaśitā mahimā. Aṇimā... The yogis, they have aṣṭa-siddhi-yoga, eight kinds of perfection. One can become smaller than the smallest or lighter than the lightest, bigger than the biggest, whatever he likes, he can get immediately, vaśita, he can control over, he can create a planet even. These are some of the yoga-siddhis. But here it is said that the supreme yoga system is not to aspire for material happiness, neither to become distressed by the material inconvenience.
This is perfection of yoga. Everyone is trying to get out of the material distress and get some happiness, but anything material-happiness, so-called happiness, or so-called distress... Just like here, the fireworks is going on. (loud sound of firecrackers, etc., occurring intermittently in background) It is happiness for somebody, but it is distress for us. Is it not? They are thinking they are enjoying, and we are thinking it is inconvenience. So that is material way, happiness, one side happiness, another side distress. So both the happiness and distress, they are illusion.