What does Paul mean by dying daily?

Les explains that the question is whether the believer has two natures, and he affirms absolutely yes. The old nature, the old Adam, constantly pursues us, while the new nature comes from our salvation experience and union with Christ. This is a Pauline doctrine of constant warfare between the old sin nature and the new divine nature. In 'Dying Daily,' Paul means he must constantly keep old Adam in subjection and put him to death. Les points to Romans 6:13 and Romans 6, where Paul deals with reckoning old Adam as our mortal enemy and putting him constantly to death. God, in His omnipotence and sovereignty, reckoned our old Adam as crucified with Christ the moment we believe—he is dead. But in experience he is still with us and plagues us until we leave this body of mortality.