What is Yoga from the perspective of the 3 Gunas?

According to Vedic perspective, all of material nature (Prakriti) is thought to be made up of three primary qualities or “gunas.” These three gunas make up the essential aspects of all nature—energy, matter and consciousness.
These qualities of nature, or gunas, are:
Sattva – the power of harmony, balance, light and intelligence; higher spiritual potential.
Rajas – the power of energy, action, change and movement.
Tamas – the power of darkness, inertia, form and materiality
It can take a bit of contemplating to understand what these “qualities of nature” are and how they are relevant to our lives and our sadhana (yogic practice). Perhaps the simplest way for us to understand the gunas is that matter is tamas, energy is rajas and light is sattva. These qualities are described as the main components or elements of our physical universe.
The Earth Element is the realm of tamas or darkness, of physical matter.
The Fire Element is the realm rajas, of action and change, symbolized by storms with their process of lightning, thunder and rain. It indicates energy or subtle matter on all levels.
The Air Element is the realm of sattva, of harmony and light. It indicates light as a universal principle that is the origin of all matter and energy. The entire universe is thought to consist of light that moves in the form of energy and condenses into physical matter.
The universe and all of nature is inextricably linked to the gunas and are formed from them. We as people are influenced by these same qualities and processes which are at work within each of us. Both our bodies and our minds are subject to the ebb and flow of the gunas within us. Each of us is thought to have an intrinsic mix of these qualities (called doshas). It is the aim of yoga practice, in all its various forms, to bring into balance our individual mix or the three qualities of sattva, rajas and tamas. Yoga of course favors the cultivation of sattva, the guna of higher consciousness, yet all three gunas must be considered and brought into balance in both the mind and body. However, the ultimate goal of yoga is union with the absolute. This would imply that sattva is not the end goal but it is the ultimate union with the divine that we are seeking.
Hence, a Yogi could be seen as a clear, running stream. When we practice asana, meditation and pranayama (breath techniques) regularly, all the systems and functions of the body line up in an optimal flow of energy. In other words, the gunas are in balance and everything begins to work well and we start to feel the radiant, vibrant health that is our birthright. Our usual aches and pains disappear, we begin to feel naturally more flexible and strong, our sleep and digestion improve and we may sense a serene calmness or peacefulness of heart and mind. The over all “tone” of our being feels more exuberant and at the same time grounded and steady. The aging process becomes one of continual growth and discovery rather than a falling apart. A feeling of being more connected to ourselves and to others may develop, and we may begin to see the world and how we live in it in a kinder, gentler way. Yoga, in all of it’s forms, is about bringing the various aspects of our self into balanced harmony. The result is that we tap into a higher, clearer energy positively affecting all aspects of our health and well-being.