I get so tired of plain water. Here are some things I do to make it more interesting:
Add a slice of lemon, lime, grapefruit, peeled fresh ginger or cucumber
Add a spring of fresh mint or basil
Use water flavoring, like Flavors2Go.
Freeze water until slushy
Make decaf iced tea
Make flavored herbal iced tea
Freeze lemon, lime or cucumber in ice cubes (in ice cube trays) and use those ice cubes to make the glass of water appealing.
Drink from a bottle? Fill halfway and freeze. YOu can even flavor that half. Then add water (flavored or not) and the frozen block will help keep the rest of the water cold for hours.
Have a special glass. I use a plastic Tervis tumbler, insulated to keep water colder. At home, maybe there's a special crystal glass you'd feel honored to drink from?
Buy cheap neon straws at Walmart or a party store to make it seem festive.
Buy a cheap ice shaving kit (Target/Walmart) and make Snow-Cones like when you were a kid. Flavor them with Splenda syrups or Splenda and flavors2go drops.
Add your own tips!