"Relevance" and "Buying-In"
The adults I teach, most of whom are "returning to school" in an effort to improve their lives, really need to see that what they're doing will impact them positively in the future. Whether I am teaching speech, ethics, writing, or history, I try to present situations in which what they are learning will benefit them. As part of the first meeting, I discuss with them their chosen career paths and point out how things we will cover will "tie in," so to speak.
Students in the writing courses, especially those students who have not taken an English class in several years, are perhaps the most apprehensive. I emphasize the importance of communication skills, which will benefit them down the road. Students in public speaking class are often very frightened, but we do several sessions of "practice" before the final speech. I think that helps.
The adults I have had seem to really focus as this is a career change for them and they have to work extra hard because of the responsibilities they have at home as well as school. I hope you find a similar experience. It is good to sometimes pair an older student with a younger one they can motivate each other in different ways and dynamics