Sādhanā. SAH - duh - NUH.
One translation of this word is "the way of accomplishment".
From wiki: "methodical discipline to attain desired knowledge or goal",
Everything can be sādhanā. The way you eat, the way you sit, the way you stand, the way you breathe, the way you conduct your body, mind and your energies and emotions – this is sādhanā. Sādhanā does not mean any specific kind of activity, sādhanā means you are using everything as a tool for your wellbeing. ~ Sadhguru
The idea is that you are always in the process of attaining or accomplishing something. From the moment we wake up, until the moment we go to bed, everything in between is a process to attain or achieve a variety of particular results. Brushing our teeth is a sadhana. Taking a shower is a sadhana. Cooking a meal. Going to work. All of these things bring about specific and desired results. The result itself exists as only a seed in the beginning of the process, and as we engage in the sadhana we are watering the seed until it brings the fruit of our "work". In physics, this is the conversion of potential energy to kinetic energy.
The process is spiritual in nature. We take an unmanifest "thing" and bring it into form. In essence, we are bridging between the spiritual world (potential) and the manifest world (kinetic). An idea alone, i.e. to brush one's teeth, comes with a variety of associated thoughts and feelings. But to turn that idea into an action in the material world we have to contend with our inner reality of thoughts and feelings and produce an outer activity that mirrors the intended result. In terms of brushing one's teeth, this activity seems to be paired with enough positive emotion for most people that it is an obvious and natural part of one's daily life. The activity brings enough benefit and emotional satisfaction to outweigh whatever potential obstacles might get in the way of the choice to brush one's teeth. Energy that could have been averted to any number of other outcomes is funneled towards a particular and specific one - teeth brushing. This is very important to note, as this is how we are manifesting each outcome in our life. It is our choices that determine where we invest energy, which then becomes the variety of behaviors and activities that make up our life. Choice becomes a fundamental building block to our personal reality.
In Yoga, we talk about two particular concepts - kriya and karma. Both stem from the same etymological root - kṛ (kri), meaning "to do". Kriya is a word that means "action" but karma, on the other hand, is often associated with bondage. I like to say that kriya is an action that liberates energy, and karma is an action that bonds energy. One is the process of kinetic energy becoming potential energy, the other is the process of potential energy becoming kinetic. Kinetic energy is a series of causes and effects, i.e. karma (also known as Netwon's Third Law). Some of these causes and effects are bringing fruition that we have no control over. However, there are other causes and effects that are the result of our misuse or abuse of the power of Will.
Will is one of the powers that creates the manifest Universe. It is our personal Will, and application of it, that motivates us to brush our teeth, or do any of the other number of activities that we are engaged in in our daily life. The more habitual the action, the less power of Will might actually be necessary to accomplish the task. Perhaps this is because the nature of the nervous system is that it learns by repetition, and once the grove is sufficiently etched in, less energy is necessary for the activity to occur. In Yoga, we call this samskara. Sama meaning "same" and.. there's that word again... kara = "an action undertaken".
Note: when translating Sanskrit, there are numerous different possibilities for each word, depending on time, context and history.
We are left with mental impressions from each experience that we've had, somewhat like the light exposure from an old photograph. The more emotionally charged an event, or the more routine or habitual it becomes, the stronger the "exposure" and the more the nervous system responds. We are literally a mold of our environment, but more accurately - we are the mold of our perception of our environment, for it is our perception that is the camera lens, determining what image we are letting in to our internal screen for exposure.
A samskara, then, is the neuroplastic imprint from an experience, which then increases the likelihood of that particular karma, or cause-and-effect, to replay itself.
When we are talking about yoga sadhana, we are talking about the process of attaining liberation from these karmic binds. That is because the highest fruit of the yogic path is moksha, or liberation. The whole idea of enlightenment, which is an experience that has been revealed to us by many masters of many different traditions, might theoretically be the simplification of a human mind into it's natural state, which is one free of the conditions (samskaras, i.e. latent mental impressions about the world), and therefore a mind that sees Reality as it is.
This begs the question - what would life be like if we were seeing things as they are, instead of as we are projecting them, or coloring them to be?
Sadhana, "the way of accomplishment", is the methodological process that, when engaged in wholeheartedly, strips one back of their illusions and brings them face-to-face with Reality. The fantasies fall away, the dreams and ambitions fall away, and the "dreamer" awakens to the One Truth, which is Consciousness. To wake up out of one's own delusion means to acknowledge that our entire life has been a mental construct built for entertainment. The ego mind cannot grasp the unimaginable reality which is life without separation. Life existing as it is, without any construct placed around it. Without a label or a concept. A pure and spontaneous creative expression of the Universe, existing for no other reason except for its own divine play.
For the few who venture along this path, it can be a lonely process and even a frightening one. Many are content with the spiritual realizations and attainments that are had along the way. Many are content with setting worldly goals and achieving them. But, according to some of the saints and sages of ages gone past, none of these worldly ambitions are as sweet as tasting the fruit of the One.
It seems that these awakenings are happening in stages for anyone on the spiritual path. The sudden and powerful insight that nothing matters. That it is all a dream. That you are the Creator of this Reality. But the convincing ego-mind will continue to collapse us back into the fragmented awareness of "I" and try to keep us in this limited sense of self.
Our sadhana is designed to systematically expand the sense of self by perforating holes in the membrane we call "me". It is the application (and ultimate alignment) of our individual Will to bring us closer to a more Divine Will. The Will of life itself, in service to All for All. Because a true awakening into the realization that this is all really just You comes with the responsibility to this realization. And gradually, bit by by, by submerging our little wave back into the ocean of existence, we spontaneously decide to have better actions, better thoughts, better moods, and better feelings about life.
The "higher" way of life is a path that is entirely subjective and decided upon by the individual. But, regardless of who or what or when, we can rely upon the nature of human suffering to awaken us from our slumber. It is our pain that motivates us to make better choices. Here, we can finally define and discover for ourselves what "better" actually means.
You don't need a cavity to know that brushing your teeth is a good thing, and "better" than NOT choosing this activity (teeth brushing). You also don't need to study ancient scripture to learn how to be a good human being. Nature has bestowed us with an intrinsic intelligence, a wisdom that surpasses the intellect. I think it is just time for us to wake up and realize what we already are, and to work with what we've got. Wisdom is in you. The Guru is in you. Your sadhana, then, is the activity that you do to honor these realizations. To seek for an intelligence that is greater for you may know, and to awaken this intelligence in your body and mind. The potential is dormant. Unwind the kinetic energy of the habitual self and turn towards something greater. What does this look like? Only you can decide.