An elderly man goes to the doctor and tells him that he hasn't been feeling well. The doctor examines him, leaves the room, and comes back with three different bottles of pills.
The doctor says, "Take the green pill with a big glass of water when you get up. Take the blue pill with a big glass of water after lunch. Then just before going to bed, take the red pill with another big glass of water."
Startled to be put on so much medicine, the elderly man stammers, "My goodness, Doc. Exactly what's my problem?"
The doctor says, "You're not drinking enough water."