The Chinese character 力（li）means ‘strength’ or ‘labour’. Does it look like a man with his two arms raising up in the air while working? I think so! -----------Why? If you add two dot-strokes to 力, that would become 为(wei) which means ‘do’ or ‘doing’.------------The extra two dots seem like the drops of sweat from the body（力） who is working hard! -----------This reminds me the hard period when I harvested wheat-crops with simple knife that kind of labour work would let me consume one kettle of water half a day! ---------Few days later my green jacket would partly become white on which you could see tiny grains of salt . How much sweating for the great job!