The mountains in winter are both exciting and dangerous. David Lintern takes a look at what happens in our heads when we’re lost in the moment outdoors – whether we are ‘beginners’ or ‘experts’. A couple of months ago I had an accident in my boat on the River Findhorn. My friend Debra and I had enjoyed a glorious afternoon paddling under a bluebird sky flanked by broadleaf trees in full autumn psychedelia. We’d paddled all the rapids we’d set out to, bathed in the blissful tranquillity of the flat stretches in-between and finished earlier than planned. It was just…