After I lost 80 lbs specifically without exercise (didn't want to gain it back) I got on my bicycle for the first time in years and years. Felt like a kid again. It's my main source of exercise these days. I mostly don't do it specifically to exercise either - the vast majority of my riding is to the post office and store.
Like DRAGONCHILDE says, " It's often about WHAT you do."
And I think obsessive water drinking is . . . I don't do it.
Today I rode 50 miles in 80 F weather with milk and Gatorade for liquids, about a half gallon total. Carbs, protein, minerals are good.