一不劳而获reap without sowing/ gain without pain.
2“忠言逆耳，良药苦口”
汉英词典中的翻译为： Faithful words offend the ears, good medicine tastes bitter.
英语国家中也有一些相近的表达方式：
Honest advice may be distasteful to the recipient.
Honest advice is hard to accept.
Truth is a hard pill to swallow.
更简单的表达方式就是：Truth hurts.