Tā cóngláibù xǐhuan zuò'érlùndào, zǒngshì qīnzì dòngshǒu.
He never liked just sitting and theorizing - he always rolled up his sleeves himself.
Tips
history
From Ge Hong's (葛洪) Jin-dynasty 《抱朴子·用刑》: 坐而论道者,未以为急耳 - 'Those who sit and discuss the Way feel no urgency.' The original meant scholarly debate; today it's pure criticism.
usage
Always pejorative - implies all talk and no action. Often contrasted with 起而行之 ('rise up and do it') or 身体力行 ('practice what you preach').