으면 되다

'That's all you have to do'

-으면 되다 says a condition is sufficient — do this and you're fine: 책 하나 딱 있으면 되지 'all we need is one book', 스태프: 물을 계속 먹으면 되는 거 아니에요? 'can't you just keep drinking water?' It is reassuring by nature, which is why instructions and advice use it constantly. Compare -어야 되다, which says you MUST; -으면 되다 says you need only that and no more.