I thought this interesting
Watchtower June 1 1968 page 331
On the Joyful March to Mankind’s Millennium
'Arguing against a literal future millennial rule by Christ, some have claimed that such a teaching would chill the missionary ardour of Christians to make disciples of all nations. (Matt. 28:19,20) But not so! Today no people are more zealous in carrying out this missionary commission than are the Christian witnesses of Jehovah, who believe that the 1,000-year reign of Christ is literal and future. In comparatively few years these have grown to more than a million. Today they are carrying out this commission in 197 lands and islands of the sea and that in 169 languages. Last year they devoted 184 million hours to this work!
And no wonder. What good news they have to tell the people! They proclaim the good news that the millennial rule of Christ will begin with this generation and that it will mean ever so many blessings for the people :..'