And it's your job to keep them interested . Remember the materials, which keep adults interested and problem centered. And involvement creates interest. They will have some knowledge or understanding about something, and it is your job to use that knowledge to enhance the learning process. Negative transfer can be avoided by emphasizing new learning as something to build upon.
People resist changing ideas that they have long accepted.
Instructing them in new ideas will be easier if they are not confronted with the necessity of unlearning the old ways. Relating new ideas to known facts can effect positive transfer. Relate new ideas to familiar facts by analogies and comparisons . Emphasize new ideas, concepts or methods as better , not different from old ways. All information entering the mind is screened by an analytical procedure that rejects, or at least questions, ideas that don't make sense.