I don't think something is a game unless there is an element of victory or defeat in some form.
Channel surfing isn't a game because there is no victory or defeat in it. If channel surfing was "find x show within y seconds", then channel surfing would be a game.
Minecraft is a game because you can be defeated in it, either by accidentally killing yourself, or getting eaten by a monster. Technically, I don't consider minecraft's "creative mode" to be a game mode, but you can make games in the mode if you choose to, by setting your own goals that you can succeed or fail at. For example if you are competing against someone else to build something.
Likewise, running isn't a game, but competing against your friend to run x distance the fastest is a game.
That said, something doesn't have to be a game in order to be fun.