At the heart of the missionary effort is “enthusiasm,” so says Pope Francis. At the heart of evangelization after the resurrection of the Lord, the Apostles were enthusiastic. Literally, the words means, to be inspired in God.
“A true missionary, who never ceases to be a disciple, knows that Jesus walks with [us], speaks to him [us], breathes with [us], works with [us].” (Evangelii Gaudium, #266.)
God does measure out his Spirit. Neither should we measure out our enthusiasm for the faith!