It is a common knowledge in life that whatever is good must be moderate and not excessive. Water is good for people’s health but you cannot drink too much,you can drink to death. The human body is a system that requires a balance of nutrients in order to be healthy. As in the case of water, it is good, but its not good beyond the right point of equilibrium.
It may be easy to conclude from this that over practising yoga is too much beyond the fitness level of the body.
If you come to this conclusion, it means that the yoga in your head actually corresponds to one of the Eight Limbs. But yoga is a system, not just Asana. Yoga is not about postures, at least not just postures.
So, too much Asana may not be good, but there’s no end to the Yoga practice. For example, you practice postures like crazy, be careful, you may have been against YAMA. Being obsessed of practising advanced postures, you are not practising Aparigraha. Having injured yourself in postures means you must have missed Ahimsa.
Back to the point, the Eight limbs forms the basis of Ashtanga Yoga practices that guides yogi to Samadhi. The quote from Guruji says Yoga is 99% percent practice, 1% theory. This 99% should be an exercise in the entire Eight Limbs system.