You don't need to deliver a 40-minute sermon to someone in order to express comfort, edification & encouragement.
Here are 5 phrases that have less than 12 words, and take less than 3 seconds to say.
"Thanks for helping."
"I appreciate your attentiveness."
"So happy to hear that you're involved in this."
"I'm excited so see what the Lord has in store for you."
"The work of the ministry matters, now let's get after it!"
It's the little things that fuel those that are eager to do more for the Lord!
One more: "There's a world out there that needs to hear about Jesus...NOW GO GET 'EM...and TELL 'EM!
1 Thessalonians 5:11 Wherefore comfort yourselves together, and edify one another, even as also ye do.