Why is everyone so happy in Finland? I went there to find out

A woman in a felt pixie hat is scooping water onto stones heated by the wood stove. Hot steam is billowing in a great hissing cloud around us, and she is swinging bundles of birch logs into it before handing one to us.

"It's good for the circulation!" she beams, throwing the leaves over her shoulders and back.

I cast aside my typically British scepticism and join in. I beat my sweaty limbs with the fragrant bouquets until the heat and sweat become too much and I walk out the door and sink into the deliciously cool waters of the ...