It clears my mind. It makes me feel less puffy after a big breakfast. I can take quick detours because some random store is a few blocks away from where I am at any given moment - doing that by car would be a parking nightmare.
I love taking the folding bike out of the house, and then meeting my wife/daughter downtown - we'll all go back by car (public transportation here is terrible, so a bike is much more pleasant!).
Recently I've been taking detours through country roads, paved or unpaved ones with little to no traffic. They are fantastically beautiful.