As long as the foot does what it's meant to do, and the hand does what it's meant to do, their work is natural. Same with a person — as long as he does what humans are meant to do, his work can't go against nature. And if it doesn't go against nature, then it can't harm him. But if happiness really came from pleasure, then why do thieves, corrupt people, murderers, and tyrants get so much pleasure?
As long as the foot doth that which belongeth unto it to do, and the hand that which belongs unto it, their labour, whatsoever it be, is not unnatural. So a man as long as he doth that which is proper unto a man, his labour cannot be against nature; and if it be not against nature, then neither is it hurtful unto him. But if it were so that happiness did consist in pleasure: how came notorious robbers, impure abominable livers, parricides, and tyrants, in so large a measure to have their part of pleasures?