I find I use counting to help me tackle the big jobs. When I look out at the deck with a freshly fallen 18" of snow I could get overwhelmed and not even want to start, but once I get out there I map out a section to estimate and challenge myself to clear it in, say, 30 shovelfulls. Before I know it, the job is done. I guess I started doing this in college when I'd come home for the weekend and have to shovel out the horse stall that my little sister had ignored all week.