I have got my senses. As soon as I use it for my satisfaction, it is material. And as soon as I use them for Kṛṣṇa's satisfaction, it is spiritual. That's all.
Try to understand the distinction between material and spiritual. Material means I have to act. Acting means I have to act with my senses, with my desires, with my thinking, feeling, willing, so many things, because that is original. You cannot stop your thinking, feeling, willing, working, because that is your original nature. You are living entity. If you have no thinking, feeling, willing, desire or working, then what is the difference between you and the stone? You are not stone. Some philosopher are trying to make you stone, but that is not possible. You cannot become stone.
So the whole process is to rectify, to purify your senses. And the purified sense means instead of using the senses for this so-called material happiness, one has to utilize the senses for happiness of Kṛṣṇa. That is purified sense. The example, the vivid example, is Arjuna. Arjuna was not willing to fight to satisfy his senses. He thought that "If I do not kill my brother or nephews or my grandfather or my teacher, the other side, that will make me happy. If they are killed, then where is my happiness?"