How can I deal with rejection?

Dear Literary Ladies,
I know that rejection is part of a writer's life, but every time something I've submitted gets turned down, I just feel crushed. How did you learn to cope with it, and not take it personally?

After leaving Prince of Wales College I taught school for a year in Bideford, Prince Edward Island. I wrote a good deal and learned a good deal, but my stuff came back except from two periodicals the editors of which evidently thought that literature was its own reward, and quite independent of monetary considerations. I often wonder that I did not give up in utter discouragement. At first I used to feel dreadfully hurt when a story or poem over which I had laboured and agonized came back, with one of those icy little rejection slips. Tears of disappointment would come in spite of myself, as I crept away to hide the poor, crimpled manuscript in the depths of my trunk. But after a while I got hardened to it and did not mind. I only set my teeth and said, “I will succeed.” I believed in myself and I struggled on alone, in secrecy and silence. I never told my ambitions and efforts and failures to any one. Down, deep down, under all discouragements and rebuff I knew I would “arrive” some day.

—L.M. Montgomery (author of Anne of Green Gables), The Alpine Path, 1917