I can really relate to the challenge you've defined here athleticsfreak. I'm in my eighth year as boys and girls CC coach at a rural/suburban high school, and motivation and inspiration are a constant challenge. I do have a few suggestions that worked for me.
First, explain and constantly reinforce the character traits that you believe will contribute to a positive team culture. Explain how these traits lead to individual and team success.
Secondly, tie these character traits into an effective and sound training philosophy and program. If the kids who listen and get on board are successful, others will follow.
Finally, be patient. It takes years to cultivate a postitve team culture and build your program. When I started, I had 1-4 kids show up for summer runs, the athletes would complain about the workouts, the upperclassmen would teach the freshman where to hide to dodge workouts, and many of the runners were "partiers."
Over the years, things have turned around. The upperclassmen and top runners model the positive character traits and the new runners buy into it. I have 80-90% participation at summer runs, the team has grown, and we've been successful.
I hope this helps. keep the faith!