Zen Master Dogen instructed,

Someone said, “I am sick. I am not a vessel of the dharma. I cannot endure the practice of the Way. Having heard the essentials of the dharma, I wish to live alone, departing from the world, nourishing my body and taking care of my sickness until my life is over.” 

This is a terrible mistake. The sages in the past did not necessarily have golden bones. Ancient practitioners did not all have superior capabilities. Not such a long time has passed since the Buddha’s death. Even in the age of the Buddha not everyone was sharp witted. Some were good and others were not. Among the monks, there were some who did incredibly evil things, and others who had a very low intellect. None of them, however, demeaned themselves or failed to arouse bodhi-mind; none failed to study the Way on the grounds of not being a vessel of the dharma. 

If you do not learn and practice the Way now, in which lifetime will you become a person of capability or a person without sickness? Just do not think of your body and mind, arouse bodhi-mind, and practice. This is most important in learning the Way.