The meaning of Tummo is wisdom fire. Tummo helps to burn all of your chakras, even the most subtle. Lu Jong and Tsa Lung do not reach them all; there is still more left to burn. Tummo is a physical movement practiced while holding the breath in a special way while also visualizing. Through the combination of these three elements you generate an inner fire which burns all of the chakras, including the most subtle left out by Lu Jong and Tsa Lung practice. This fire will burn all your past bad karma. By this we mean that it burns the karmic imprints. We are never free of our karma because we are never free of our imprints. Imprints are chakras. It is not necessary to physically burn all the past bad imprints, bad karmas and bad memories because our chakras are so subtle that they are invisible. With normal techniques it is impossible to open these chakras; they must be burned. What does it mean to burn a chakra? If there is no chakra, this means there is no blockage. We say it is then a channel, but this does not mean it is like a tunnel or pipe, because these are physical things. By channel, we just mean that there is no blockage. The fewer blocks you have, the more open you are. You continue to open and open until at some moment you are just endless. Your heart, your energy, your love—all becomes endless. This is what we call a channel. And to achieve this we use the inner fire wisdom.

If you still want to go even deeper, then you need to do bliss meditation.