Easier said than done

Idiom: "easier said than done"

Definition:

More difficult than you think

Examples:

1) You want to get an A in my class?  Easier said than done!

2) Starting a new business is easier said than done.

中文解释：http://www.youzienglish.com/main/idiom_of_the_day/easier_said_than_done/cn/