I drink it straight from the tap. In the summer, I'll add some ice, but about 3/4s of the year, it's cold enough for me from the tap. I don't measure it anymore, but I did when I first started. I had to force myself to drink it - I had been used to diet sodas all the time before. These days, after having my morning coffee, I fill up the glass and just stick with the water all day long... even with my meals. If I have soda now, it's a treat. Ironically, I like using my Coca Cola glass for drinking the water. It holds 20 oz. so I fill it up 3-5 times per day.

Another trick I read about somewhere is that you should fill up your glass everytime after you go to the bathroom. It's an easy way to remember.