Tapas, Svadhaya and Isvara Pranidhana are considered the 3 basic actions of yoga. These words have no single translation but you could say that the actions are self-discipline, self-study and self-surrender. This at least gives a better understanding but it also loses the richness of what is trying to be said which is why it is good to stick with the Sanskrit.
Tapas – Forget about Spanish bars and eating tasty morsels. Tapas means fire, to heat, to glow, to shine, to transform, self-discipline, austerity, purification, penance, continuity of practice. This conjures for me the image of the Phoenix bird that builds itself a nest of fire and then burns itself in order to regenerate and start again, very much the same as the Australian bush where some plants require fire to regenerate and have a storage system that allows this regeneration.
I destroy and create myself like the sun that rises burning from the east and dies burning in the west. To know the fire, I become the fire. I am light. I am forever. The heat of transformation is unbearable, yet change is necessary. It burns up the useless. – Egyptian Book of the Dead
So while on one level the action behind Tapas could be seen to mean using your self-discipline to establish a regular yoga practice, it also suggests that such an action will provide stores of energy and resilience that will enable a constant process of self-renewal and growth.
Svadhaya – Forget about a potential name for your new pet dog. Svadhaya means becoming closer to our true self through study and inquiry.
In yoga there is the small s self and the big s Self. The small s self is considered the story we create to operate in the world through self-talk, habits, beliefs, memories, ideas, prejudices, preconceptions, plans and ongoing internal chatter. The big S Self is considered our true nature that is always there and exists beyond our thoughts, our emotions, our activities and beliefs. Svadhaya (Self-study) means looking at both these selves and learning to distinguish between them and to change and shift the small s stuff when it is not serving us.
Through self-study we build our powers of discrimination, self-regulation and are better able to make decisions and choices, including physical choices about what we can and cannot do with our body. The latter is often limited by the self- talk and the fear this creates. Regular practice (tapas) together with self-study can transform that self-talk, burn the useless, the negative and provide a new way of being in the world, however the ultimate goal in yoga is to tap into the Self (big S).
Savasana is considered the most important and advanced asana because it is asking you to let go of the identity that you have created and tap into the Self. This means “stilling the fluctuations of our mind” which is a lot harder than stilling the movements of the body. BKS Iyengar refers to this time as a shedding of our skins, a shedding of the stories we weave to form our identity, a shedding of our thoughts and in doing so revealing how “glossy, gorgeous and serene is the beautiful rainbow snake that lies within.” The practice of yoga offers ways to clear the noise, the dirt, the fear “the smoke around the fire” that is stopping us from being able to see our own true self.
Isvara Pranidhana: If you are having trouble pronouncing this one just ask yourself Is Vara Pran in India? and you will be close. Isvara means true self, universal consciousness and Pranidhana means letting go, surrender, wholehearted dedication.
Isvara Pranidhana is about not fighting the poses, going into the experience of a pose, finding effortless effort, having no expectations of results, no fear of success or failure, surrendering to what will be, feeling connection with all around you and learning to surrender. At the moment I am reading The Little Princess by Frances Hodgson Burnett to my daughter where the central character is a young girl who survives hardship by letting go of expectations and waiting for the magic:
“Somehow, something always happens,” she cried, “just before things get to the very worst. It is as if the Magic did it. If I could only just remember that always. The worst thing never quite comes.”
Mastering more difficult poses requires regular practice (tapas), self-study and a letting go of any expectations of results. Slowly very slowly the magic will arrive and the pose will come to you. The future is taken care of moment by moment and does not correspond to anything imaginable. So here’s to the magic of Vara in India who is eating Tapas with her pet dog Svadhaya.
 BKS Iyengar, Light on Life: The Yoga Journey to Wholeness, Inner Peace and Ultimate Freedom