Evangelism - a duty or delight?

I came across this the other day from JI Packer:

Harry S. Boer wrote telling of the naturalness of evangelism in Pentecost and Missions (1961). There he shows that the view of evangelism as first and foremost a Christian duty required by the Great Commission of Matthew 28:19-20 is no older than the last century, prior to which the mainspring of evangelism among lay Christians was the naturalness of sharing Christ with one's neighbour out of sheer inner excitement over the new life of hope one had found.

Packer continues:

...But during the past century Christians have become unbiblically and indeed pathetically earthbound, concentrating their hopes of happiness on the here rather than the hereafter. And as the glow of the hope of glory has faded, credibility has diminished, and zeal for sharing Christ has waned.

Meantime, evangelism has been institutionalised in various forms and programs of organised mission activity, thus becoming a duty rather than a delight.

Celebrating the Saving Work of God, p208