I remember ignoring this advice at the Grand Canyon, and regretting it. I was in my mid 20's, the weather was mild, the walk was wonderful, until I started to think I might not survive it. A few years later, on a warm Florida day, I learned the hard way why serious bikes have bottle holders when I headed out for 20 miles ride, in an isolated area, without water. I never made that mistake again.
There is usually a glass of water within my reach. For years it was diet coke, or coke-zero. I cut back on those, and then this year between traveling the first couple of weeks in March and being home, well I have had one coke zero since March 16th. Just one. I have broken that addiction. Water is likely healthier. It is lower in cost. At home it is in a glass, so there are no single use plastic bottles to clutter up the earth for a decade or more. Better for me, better for the earth.
I start off the morning with a very large iced coffee, the stronger the better. You shouldn't be able to see through coffee. From there on it is water for the rest of the day.
What drink is within arms reach for you?