The saffron robes and the shaven head are not essential, although they create a good mental situation, just as when a military man is dressed properly he gets energy-he feels like a military man. Does that mean that unless he is in uniform he cannot fight? No. In the same way, God consciousness cannot be checked- it can be revived in any circumstances -but certain conditions are helpful. Therefore we prescribe that you live in a certain way, dress in a certain way, eat in a certain way, and so on. These things are helpful for practicing Krishna consciousness, but they are not essential.
Source: A.C. Bhaktivedanta Swami Prabhupada (2014 edition), “The Science of Self-Realization”, Page 186