The motivation changes year to year. When I first started (as a 11 year old kid) I bought all the tags I could afford, and did my best to use them. Then I went through a couple years where I would shoot doe but waited on a nice buck. These last two years I'm back to just enjoying the hunt and not caring about what the rack looks like. But ultimately it is because I like to shoot deer. I am in the woods year round. In the off-season I am hiking, mountain biking, bicycling, dirt-bike riding, kayaking, fishing, rock climbing, taking pictures, and doing anything I can to be outside. So, I could say I deer hunt because I love being in the woods. But I could be in the woods for a lot cheaper than it costs me to hunt each year. So, I do it because I love to hunt. I like the meat, and there's nothing like arrowing a deer, or putting the crosshairs on one.
I also enjoy the challenge it gives me. I could go out anytime I want and shoot a deer. But every year I add something to keep the process evolving. Last year I started still hunting with the bow and had the time of my life doing it.
-Jake