Nondrug high/altered state experience thread

[Heretic.Ape.]

I'm interested to know what kinds of experiences the various hedonists and psychonauts out there have had with nondrug methods for obtaining highs and altered states.
Examples of altered states might include things like lucid dreaming, hypnosis, holotropic breathwork, different forms of meditation, visualization, tantra, etc.
Highs could be any number of things including the above and things like methods of releasing endogenous endorphins/neurotransmitters--runners high, bsmd practice, yoga, dancing, etc--or cognitive tricks and such.
All comments and experiences are welcomed and greatly appreciated.
I have had experience with runners high, various types of meditation, ecstatic contemplation and other things that have had varying and unreliable success.