lower one's expectations：降低某人的期望，引申为期望过高。

【例句】
There are always two ways to be happier: improve your reality, or lower your expectations.
总有两种方法会让你更加开心：改善现实或降低希望。

Students hold that the highest expectations of happiness of love relationship, marriage, and family, but unexpectedly much lower expectations about work, life and salary.
大学生在对幸福生活的期待上，爱情、婚姻、家庭幸福的期望值最高。而对工作、生活、收入的期望值都比笔者想象的低很多，对自我的肯定值也偏低。