Well it's not necessarily laziness, but the need to do such things. Riding a bike yeah, if you've lived in the city and need a quick ride around (aka too young to drive) I could see that being a situation, but whistling? Yeah, you don't need to whistle, and your life won't depend on it, unless, you know, a homicidal maniac forces you to whistle while your guts a spilling onto the floor below :P