An interesting excerpt from an article titled "An introduction to understanding the science of Prana Tejas and Ojas" --
Prana is responsible for the adaptability and creativity of the psyche, without which we suffer from depression and mental stagnation. Tejas govern mental digestion and absorption without which we lack clarity and determination. Ojas provides psychological stability and endurance without which we experience fear and anxiety.
And some additional words from Robert Svoboda --
Prana is the energy that drives life, the power that animates the body, enlivens the mind, spurs the soul. Prana is life's inspiration, its foundation, its tenacity; it is the sure hand on the tiller, the wise voice of good counsel, the urge to health and harmony that craves to turn our bodies into havens where we can take shelter from the storms of the hectic modern world. Prana is at work at every instant in every cell of every living organism, seeking ever to deliver us from disease and confirm us in health, but only in those few people who are genetically fated to be healthy does prana automatically regulate its momentum. The rest of us must learn how to cultivate our prana.
And some additional words from Robert Svoboda --
Prana is the energy that drives life, the power that animates the body, enlivens the mind, spurs the soul. Prana is life's inspiration, its foundation, its tenacity; it is the sure hand on the tiller, the wise voice of good counsel, the urge to health and harmony that craves to turn our bodies into havens where we can take shelter from the storms of the hectic modern world. Prana is at work at every instant in every cell of every living organism, seeking ever to deliver us from disease and confirm us in health, but only in those few people who are genetically fated to be healthy does prana automatically regulate its momentum. The rest of us must learn how to cultivate our prana.
...
Understand your natural affinity with prana and you gain insight into which method of prana cultivation will work most efficiently and effortlessly for you. Sound prana handling is methodical, and the rishis, India's seers who spent their long lives poring over the many facets of the paradox that is life, proposed an variety of methods to encourage prana to adopt an suitable pace. They advised at the outset that we use the principles of Ayurveda, India's life-science, to balance vata, pitta and kapha, the three energy strategies of embodied beings. These Three Doshas encourage ailments when they are permitted to struggle with one another, and work to support the organism when taught to cooperate. When the Three Doshas strive toward amity they serve to strengthen agni, or tejas, the fire of transformation that permits us to feed and nourish ourselves. Strong fire digests cleanly the prana that we consume through our breath and through our food, and strong agni and prana facilitate the development of ojas, the pure "juice" that makes living worthwhile by cementing together body, mind and spirit and fueling immunity from illness.
Strong tejas and ojas in a body provide prana a good seat (asana) there. Well-seated prana provides us the visceral resolve we need to perform our every action precisely, rightly, with great resolve and enthusiasm. Such a body moves not from obligation but from the joy of movement that is prana's nature. Well-seated prana enhances immeasurably our ability to perform any yoga posture (asana). As prana becomes carefully settled through the practice of asana our bodies become fit for pranayama, which can promote control of the senses and the mind. Breath, prana and mind are mutually and inherently related; cultivate one well and the other two will fall into line. While many yogis do use breathing exercises to cultivate prana and mind, others use meditation to regulate the breath and prana. Some practice Svara Yoga, control of prana and mind by means of song, and some align breath, prana and mind by means of undiluted devotion to Divinity.
