I often forget how most people consider yoga to be simply physical exercise. More people are discovering yoga in gyms in North America than in the many yoga studios that seem to be on every street corner. Of course, we have to get a bit more creative in rural areas. The way the public thinks about yoga is quite telling. One of the fundamental challenges we face, according to yoga psychology is our over-identification with the body. That means we fail to recognize our psycho-spiritual nature (for the most part). Human beings are like ice-bergs where there is more going on than meets the eye.
Any activity that is intended to re-unite our fragmented experience of reality can be classified as yoga. Even living in an ashram for 10 years there were many people that continued to say, "this is yoga and that is not yoga" Well, unless you could see into the heart and mind of that individual how could you possibly know if they were practicing yoga or not? We go to a class and get on a mat so that we can learn to concentrate the mind, strengthen the body and improve our health but the practice of yoga need never stop. You are continually faced with your perception of reality and the myriad of ways your ego reacts to that perception. Simply being aware of this process is a yoga practice.
To say, "I don't have time for yoga", then is the ultimate misnomer. It is time to deepen our understanding of this ancient practice. One translation of the above statement could be, "I don't have time to remember who I am". I would say it is more a function of space than time. Learn to create space in yourself and time will loosen its grip on you.