This is the secret of the DXM Angel.
This has been taken to mean that spontaneous awareness is constantly accessible. When you say "It's happening", it does.
It could also be taken as an assertion of existence as it is experienced - embedded in space and time. It's Happening In The Place is a rejection of behaviourist or functionalist accounts of consciousness.
Be here now
It could be read as a reminder of the perfection and reality of each experience. Are you looking for truth? Well, truth is right here; it is disclosed to consciousness at every moment. It's Happening In The Place.
Body and soul, baby
The DXM Angel tells us to "do xercise more". This is the clearest xpression of physicality we've seen from any of the gods. Also, the DXM Angel is the only god with a humanoid body. General Miaow is almost always drawn without a body, Thomas the Walking Head's body is conspicuously absent, A Magical Trumpet Called Bill has a face, but no body, so The Reality Fish is the only other god with a body, but, that doesn't count because, well, it's a fish. With this in mind, consider the secret It's happening in the place. In context, it means "Consciousness is happening in the body". It seems that the DXM Angel is responsible for the fact that our consciousness is in a pile of meat.