As in most things Far Eastern, one is not supposed to strive for or focus on their objective to attain it, but is supposed to engage a mind-set of indifference to the objective, or even thinking in terms of being against the objective, while continuing one's practice in a responsible but somewhat mechanical adherence to repetition, and trust in the notion that the desired change (or experience, or windfall, or achievement) will come about, will happen, will become theirs, when the time is right, when they are ready for it, when the universe is in alignment with them.
Finding one's chi is somewhat akin to a person, blind from birth, finding the way to understand color in the way a sighted person experiences it. Can we really say the sighted person "understands" color, or must we limit the scope of our pronouncement to "the sighted person experiences color"? The average sighted person when asked "do you understand color" will answer, "of course I understand color", thereby mistaking his experience for understanding. The blind person, no matter how good his vocabulary or how vivid his imagination, can never have the experience of experiencing color the way a sighted person does. Therefore, he can never truly understand the nature of color the way sighted people do. He can substitute intellectual understanding. He can study the nature of wave propagation, the spectrum of electromagnetic energy, the additive and subtractive qualities of pigments and of light in producing color, etc., but until the reality causing his blindness is subverted, he will not partake of the uplifting experience of color.
Fortunately, finding one's chi, is not as doomed to such unlikeliness. But the problem, in both cases, is that the experiencer has no physical analogue, no physical conceptualization, no experience of what to look for, what to strive toward, no 'physical' understanding of what to try to make happen. But, according to traditional teaching lore (belief), continued, diligent, mindful practice has the best chance of producing the desired end- the experience of feeling chi flowing within you. Once it is felt, no matter how short the length of time of the experience, no matter how small the distance traversed of the chi flow, you now have a physical analogue, a sense in your repertoire of sensations, to attach understanding to- at the very least, to be able to recognize the experience for what it really is the next time it happens.
Chi is a generic term (in English) to cover a multitude of notions (in Chinese medical thought): Breath, air, the oxygen in the air, blood, the oxygen transported via hemoglobin in the blood, nerve impulses, the flow of life force along meridians (or channels), the energy from converting 'brown fat' to glucose, seminal fluid, body heat, etc., are among the most common of these notions. My own contribution to this list of non-tangibles, arising out of my own studies, reading and analysis, is the notion of "intent". For my purposes of understanding and teaching, "Chi" can be thought of as synonymous with "Intent". It is clear to me that when one intends for a specific thing to happen, such as a fist strike to an opponent's jaw, the origin of the action is in the brain, and a variety of things must "flow" from one place in the body to another in order for that final objective (the strike) to be achieved. Nerve impulses must travel from the brain to the muscles required to produce the strike. A whole host of chemical reactions must occur to provide the electrical and mechanical energies involved in the generation of movement and the timing aspect with regard to the coordination of the turning of the waist with the forward motion of the body and the release of the strike. All require a lot of back and forth flow of information throughout the entire body- all to produce a physical action (movement), that originated in the brain as a thought- This amazing internal dance, in its entirety, from thought to connection with the jaw, can be wrapped in a single, simple, unifying concept, I call "intent".
Everything one does, from first breath to last, including the beating of the heart and the rise and fall accompanying each intake and exhalation of breath, can be seen as attributable to intent. Granted that some actions are governed, controlled, intended by autonomic systems, while others are at the behest of conscious choice, but this is not a meaningful distinction because there is no autonomically controlled system that can not be taken over by conscious control. Anyone can learn to hold their breath, slow their heartbeat, raise or lower their blood pressure, alter their body temperature, etc. A big part of Tai Chi practice is about many of these abilities, not the least of which is developing the ability to release the tension in the muscles of the upper body, and slow the breath. By intent!
If you engage (harmonize) these ideas as you engage your Tai Chi practice, moving from posture to posture with a sense of intention that initializes with the yin and culminates with the yang, intentionally sinking back into yin, going slowly enough to connect the physical awarenesses to the mental processes and concepts, I hypothesize that you can (and will) progress and develop toward a transition, a bridging of the disconnect between the physical and mental systems of experience, unifying the two into a new awareness; you might say, into being able to understand the true nature of color. This lofty objective is in keeping with the true ultimate objective of practicing Tai Chi, that being the unification of mind and body into 'mind-body'- Living one's life as a unified entity- Mind (Spirit) and Body functioning in harmony as a unified whole.