Energy
This is a big topic. In fact, it's the biggest topic, and, in a sense, the only topic. I could give you the usual jawboning about the possible reality or physical/metaphysical correlates of the qi concept in classical Asian thought. But I won't. That can be boring and anyway it is covered elsewhere on the web.
I have many drills and routines for cultivation of internal qi energy (or ki in Japanese). The fundamental method, however, is the Cheng Man-ch'ing taijiquan form. You can see the "Instructor" page for some (not all) of the additional practices that I've intensively trained in.
But let's talk more fundamentally. Here's the universe:
Matter is contracted Energy
Energy is contracted Consciousness
Consciousness is contracted Love
Infinite Love is the only Truth
The first three are my personal assertions based on experience. The final assertion is well established in Western physics (matter is sometimes referred to as "lumpy energy"). By developing our personal understanding of pure energy, we are returning to the Source.
A wanderer returning to the Source