Trying to be a "Green Athlete" for me is about doing my best to limit what I use. The saying goes: "Reduce, Reuse, Recycle" it is not the other way around. The first thing we need to look at as athletes is how can we REDUCE the damage we do or REDUCE the amount of stuff we use or throw away. One simple way that I have been doing is with bottled water. Instead of buying all those small bottles of water from the store buy the gallon or 5 gallon water jugs and just fill a bunch of small bottles for each day. Or even better than that why not save your money and just buy a filter for your tap water. Most tap water is descent and just needs to be filtered with a Brita or PUR filter and it is as clean as the water you buy in the store. They are relatively cheap you can help REDUCE the amount of empty plastic bottles that are filling up our landfills.
Start by doing some of the simple easy things and don't worry about being the perfect "green" person. If everyone one did something little it would make a big change.