1) Refuse the goodie bag - if you find that when you run a race and realize that you toss out all of the promotional items, then, it is best to refuse the goodie bag. If you like getting the promotional items, you can bring your own shopping bag and refuse to take the plastic bag with you.
2) Ask the race administrators to use paper or eco-friendly cups instead of the styrofoam cups.
3) Remember to throw the cups into the trash and do not litter along the way. Some race volunteers might clean up afterwards, but it's best to clean after yourself.
4) Reduce your carbon footprint and carpool to/from the race whenever possible.
5) Choose quality over quantity when it comes to running shoes, running t-shirts and shorts.
6) Run outdoors (to reduce the need to use treadmills and electricity whenever possible) but be smart and run with a friend or group of friends.
If you have additional ideas or suggestions on how to run in a more eco-friendly way, please feel free to share.