Energizer games and ice breaker activities to bring energy into the room. Get people moving, have fun and make sure your group's energy level is right to continue with your session. This a simple icebreaker activity energising participants, also suitable for debriefing learning.
The Isn't that crazy energizer is amazing for getting people talking and collaboratively creating a story (usually a funny one). It fosters engagement and everyone.
If you think they'll dislike classroom activities for adults, you're wrong. Small classrooms work better though, but energizers in the classroom.