“All Life is Yoga” means that all we think and feel and do, the entire field of our thought and will and actions must become a conscious yoga.
Ordinarily it is only a subconscious yoga in the sense that indirectly we are ultimately seeking some kind of a perfect state of peace and joy and harmony and love and knowledge and power. But we are seeking it unconsciously through the play of ego and desire. We try to find these things through outer objects and people. The result is a mixed lot that soon frustrates us because we realise it is limited and imperfect. This subconscious yoga is going on in creation and through this process we slowly move towards the growth of our soul and unfolding of the Divine in us. This is a long and subconscious process.
When this seeking becomes conscious and we begin to aspire for the Divine concentrating our energies upon Him and offering all our activities and movements and thoughts and feelings to the Divine then all life becomes a conscious Yoga. Until this happens, we have to use the sense of right and wrong to navigate through life and receive the experiences and go through the consequences.
All life is yoga does not mean doing all actions without consideration of right and wrong. We have to make our choices since it is through the choices that the future path opens for us. In ordinary life, the choice is based on social, moral, ethical considerations which often differ from age to age and place to place. In yoga however the consideration is based on what brings us closer to the Divine and what veils His Presence, or with regard to the world what helps humanity grow Godward towards Light and Truth and Unity and Light and Beauty and Good, and what draws us towards division, disorder, disharmony, ugliness, crudity, cruelty, darkness and falsehood. It is this choice that indicates our sincerity which is a fundamental requirement for the yoga.