It's easier said than done.

(traditional) 説起來容易 做起來難 / 站著 説話 不腰疼 

(simplified)  说起来容易 做起来难 / 站着 说话 不腰疼

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say, speak    説，説話//说，说话

difficult   困難，難//困难，难

著/着   after a verb, means keeping the action status. E.g. 站 means the action "stand"， 站著/站着 means continue the stand action    

hurt, ache  痛，疼，疼痛

站著説話不腰疼/站着说话不腰疼 literally means when a person stand talking, no waist ache. He should try to sit talking, then he will know the waist will hurt. So actually means it's easier said than done.