joie de vivre 
生きていることの熱望的な喜び
1.French. a delight in being alive; keen, carefree enjoyment of living.
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英次郎
Longman
Citations for isonomy
It's this sort of thing that ages a chappie, don't you know, and makes his youthful joie-de-vivre go a bit groggy at the knees.
