I'm not sure this counts as a "happy story", and it is only very short, but it wandered into my head as a result of rysmiel's suggestion. It's not an unhappy story, anyway. But if you want something more amusing, I propose Ogden Nash's poem "The Eel":

I don't mind eels
Except as meals.

EEL

There's a river, rippling and cold, and rising up from it are a pair of skinny legs. They're my legs, and they're as statue-still as the rest of me as I stand in the water and stare down into the sparkling dark. Sunbeams bounce off swirls and eddies, glint on the edges of leaves and rushes; they look like a thousand fireflies. But it's not the sunlight I'm staring at; I'm watching the weaving and winding of an eel.

It's writing on the riverbed; it's scribbling its way home.

Time stands still, and the slow summer air stands stiller, stagnant; the only movement is the midges over the water. An observer lazing on the riverbank would see my pale and angular body poised against the haze like a cool sharp knife-edge, like a guillotine waiting to fall. He'd see me standing straight and tall, and his own immobility would alter subtly; no longer lethargic with the heat, his senses would sharpen in tune with mine. He too would be watching, waiting.

I follow the eel's progress with an unblinking eye. You have to choose the moment carefully.

Suddenly I dive forwards, slicing through the silence, slipping my head swiftly into the water and snatching the eel up. Just one swallow and it's sliding down my throat, its wriggling restricted, caught in my trap. It is cool and smooth as it slithers its way down, and in that moment I know total satisfaction: I have food, and the sun on my feathers, and water lapping at my feet, and it does not matter to me that there is no observer lazing on the bank, no parent to shout "look, a heron!" to their child as I spread my wings and rise from the river to the sky.