When I'm sad, I try and lift up my spirits by recounting past moments of happiness.
Its silly but when I was on the bus a few days ago, it was stopping abruptly (due to the traffic) - I was standing and started getting motion sick.
So I recalled the times when I was skiing with my friends, I remember the times when I was on the ski chair lift- and how it took had that swaying stopping motion. Of course, it also didn't have a dozen Indian and Burmese migrant workers in the chair lift- but I closed my eyes and imagined :)
Now everything's white, I see my friends Jensen, Joy, Sam... skiing down the mountain, I wave towards them, then I get off the chair lift and start skiing down the hill, knees slightly bent, be relaxed, turn left then right... I feel the cold of the wind, the freshness of the snow, and I'm back at Falls, Perisher Blue, Cardona, Hotham, Bulla, Remarkables... Jesus, its good to be alive.
Having a thankful spirit does wonders.