Easier said than done

Meaning

Acknowledging that a task or idea sounds simple but is actually quite difficult to execute. It is often a polite way to tell someone their suggestion is unrealistic.

Realistic, cynical

Used in a sentence

• You want me to retire at forty? That is easier said than done.
• Fixing the car engine sounds easy, but it is easier said than done.
• It is easier said than done to just quit your job and travel.