Lack of exercise prevents energy from moving through the body, which can cause stagnation, blood coagulation, muscular atrophy, etc. but most people who live normal lives with at least some walking can avoid major issues related to being virtually motionless. Yoga asanas help to release traumas stored in the physical body over time. So yes, there is definitely a need for physical exercise but nothing above and beyond what a normal "day in the life" entails. Even walking roughly a mile a day is more than enough generally speaking.

Our "natural state" is one of perfect health, harmony and happiness. Obviously, the "normal state" of most people has been severely disrupted by belief in a cavalcade of lies and deceptions and this explains the ill health of so many today, from diabetes and obesity to cancers and "auto-immune" disorders and everything in between. All are caused by disharmonious thoughts that have their origin in fear and judgment.