Don't you find this tactic tiresome? I get frustrated by those "greener than thou" individuals who make passive aggressive comments to make a point. Instead of saying, "I think it is wonderful that you are taking the time to get in shape. But, did you know that the plastic in water bottles can leech out causing potential health risks? What about switching to a stainless steel bottle?"
Now.....don't you think they will be more receptive to that type of comment?