When I hear the word "spirit," I think it's the old Catholic in me that makes me automatically think "ghost" or "soul." It's the part of us that remains once our bodies have left this earth. Our spirit is our "essence."
It makes me think of the people I've loved who are gone, and that in the times I miss them, or dream of them, they are still very much a part of my life. I like to think they're looking down on me approvingly when I get things right, and shaking their heads in mock disgust or having a good laugh at my expense when I screw things up.
My senior year of high school, my good friend, Jennifer, died in a ridiculously preventable car accident. She wasn't wearing her seatbelt, and was in a car with someone driving recklessly...the usual I'm-an-immortal-teenager crap. She had just turned 18.
Jennifer had a spirit full of energy and life. She was wild and spontaneous, goofy and fun, spunky and silly. She knew the value in a good laugh better than anybody I knew then or have met since. When she died, I remember thinking that there was no way all that spunk could just be gone. I took comfort in the thought that her spirit would live on, even though her body had not.
Because our spirit is the most important piece of us. It's our soul, our essence, the part of us God cares most about. Because it's who we are.