It can happen on the way home from the chiropractor, or just sneak up on you without warning - the rediscovery of the wonder of life without pain.
It is perhaps the purest form of happiness, pure in that it depends on no external input, no kindness, no favours. No achievement, presents or promises. I have seen the same argument advanced for recreational heroin use.
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My mother learned the technique, and soon graduated to the advanced programme, targetting famous people.
1 - in the sense of "experts", rather than "enjoyers"