After about 7 years of letting myself go (which is how I wound up at 200 lbs.), then turning it around on May 14th, 2008, the biggest change I've made has been drinking, at minimum, 64 oz. of water a day.
I'd been buying water bottles before I started on my WoE, because it was a rare thing I'd actually drink water.
After 6 weeks of this...I realized I was costing us way more money than I needed to. So..I went and bought a Brita filter. Been using it for 2 days now and I have to say, the water from it tastes just as good if not better than the purified bottled water I was buying.