Happy like a fox!
Sorry, that's a bit glib on reflection!
I like to think of infinite as an approximation of happiness. When I am truly happy I feel infinite. The joy stretches out of me in all directions (metaphorically), reaching everything inside and outside, I am connected to everything in those moments. Joy is an experience that expands outwards. Whilst darker emotions are an experience that press inwards, claustrophobic, crushing, confusing. Happiness is weightless, expansive, effervescent! At least, that is my experience.
Also, as I thought Haiku's were often nature based, it was fun exploring this metaphor.
Ah yes, very nice, very nice.