All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
In his commentary on Saheeh Muslim, As-Suyooti said that lagging behind here means being lazy to stand in the first row. This opinion is supported by another Hadeeth: “Some people will continue to draw back from (standing) in the first row (in prayer) until Allaah Causes them to draw back.” [Abu Daawood, Al-Bayhaqi (Al-Albaani: Saheeh)]
Allaah Knows best.