One of the first changes that I made when I started out on my Green Journey was to switch to phosphate and chlorine free dishwasher detergent. Of course I researched why phosphate free was important and the sites basically said the same thing but I think Yahoo Green stated it best:
While phosphates are no longer permitted in laundry detergents in the U.S., they are still allowed in automatic dishwashing soaps (some states differ on the legally acceptable levels). Phosphates are additives that fight the effects of the minerals found in tap water--the minerals that cause hard water and the related spotting on dishes. Phosphates, however, also come from the same family of chemicals commonly used by farmers to fertilize crops. When phosphates wind up in waterways like rivers and coastal areas, they can “fertilize” algae populations, leading to large algal blooms which in turn can choke out plant and animal life in aquatic ecosystems. This is called eutrification, and along with agricultural runoff, can contribute to aquatic dead zones.
I also recently read a very informative post on grist about phosphates in detergents that I would highly recommend reading.
My thought is, if you know why you are doing something, the importance of what you are doing, and the consequences of not doing it, you are more apt to do it and stick with it.