I believe that deep-down, humans have a natural tendency towards laziness. I don't think this is true because we are bad people, but because throughout our evolution we developed a biological need to conserve energy in an environment where food was scarce. Today most of us live, work and play in a land of plenty. Think about how difficult it is to choose the option where you know you will need to expend more energy.
There is a large river in the state of Iowa where I grew up. Many years ago, I was invited to go boating on that river with my university friends. The part of the river that they chose was perfect for boating; it was calm and wide, and flowed strongly downstream.
The interesting thing about boating on a river (instead of a lake, ocean or other large body of water) is that you have two real options and one non-decision option. You can choose to start the boat's motor and drive upstream against the current. Or, you can turn the boat around and drive downstream with the current. If you choose to do nothing (by turning the boat's motor off or leaving it in idle), then you are effectively choosing to go downstream, at the same speed as everything else that's floating in the river.