Renunciation is the practice of detachment from desires
Being detached from one’s desires is seen as a sort of freedom, rather than some sort of hardship. Iyengar says that the only way to achieve this is through willpower.
The goal is indifference, and i suppose that means also indifference to the practice itself. This reminds me of Suzuki in Zen Mind, Beginner’s Mind stating that meditation practice should be “nothing special”. It is easy to practice when it goes well, when we achieve that asana or our mind is still during meditation. But it is easy to get discouraged when we are stiff or our mind is noisy. Being indifferent doesn’t mean that we can’t enjoy things. It’s Ok to enjoy the practice, notice that enjoyment, but do not expect it every time, or make that enjoyment the goal of practice. Similarly, it’s Ok to enjoy spending time with your children, but the enjoyment should not be the goal of that interaction, nor should we expect it every time. I find this quite a liberating concept.
The sutra does not explore from what things we should detach ourselves. I suspect it is detachment from everything that we should aspire to, even the practice itself. This is not easy, but perhaps the first step is to notice when we feel attachment to something. Try this in the course of your day – next time you want a chocolate or your child to be better behaved or to have a ‘good’ meditation session (whatever that is) just step back and think “attachment is here”. Surely the first step to detachment is awareness of attachment.