The poojas, havans, mantras and rituals are the most outwards and not indispensable means. The real means are inner which includes a one-pointed Godward aspiration that frees the inner consciousness tied to the body and then opens doors to several possibilities such as entering into the cosmic consciousness, awakening of latent powers and possibility through a concentrated evolution. It is the inner Yoga that they engaged in which is different from Karmakand or outer rituals. The logic is simple. If you know the Origin, the Source, and identify with it, then you naturally command a mastery over everything else since the Origin, the Divine is in all. It is said of the Ultimate Reality or Brahman that if you know it you can know everything and it is logical because the closer we go to the core of anything the greater the power one wields over it.
Of course this Yoga has little to do with outer exercises, physical processes and techniques but the inner alchemy as described in the Gita, the Vedas and the Tantras. The Tantra, for example speaks of three kinds of sadhaks. Those who engage only in the outer gross physical rituals, bahya pooja, those who engage in mental processes, manasic Pooja, and those, the highest type who use spiritual and inner means, adhyatma marg. While the first two may give some temporary hold over the hidden occult processes and powers behind creation, it is the last sadhak to whom all this knowledge and power comes naturally because he has grown in inner purity and not likely to misuse them. It was primarily an inner Yoga that they engaged in which gave them natural entry into the inner secrets of creation by identifying more and more with the consciousness of the Creator.