Fitness for Yoga is a very relative term—the real fitness comes by the soul’s call and the power to open oneself to the Divine. If you have that, you have the fitness, and your past actions cannot stand in the way: the past cannot bind the future. Of course, you have to finish with it, reject it and turn into the new ways—otherwise the past remains the present. But that is the question of the will in you and the soul’s call. If you are faithful to your soul’s call there is no reason why you should not be able to do Yoga. All that you have to do is to keep your aspiration and not lose the inner connection that has been made—then the Mother’s thought and the help will be with you and you will find your way.
Ref: Letters on Yoga — II