Teens are most likely to understand instructions.
With toddlers and babies, it's pretty difficult for them to cooperate since they can easily forget what they are doing. With teens, it's much easier for them to cooperate since they are older and more mature which means that they could be willing to listen.
The psychoanalytic perspective of personality emphasizes the importance of early childhood experiences and the unconscious mind.
I dont have the answer to every answer but I can help you with 3.
3. I think people are motivated in different ways, one way might work for someone while on the other hand it wont work for someone else. When I think of this question its hard to come up with a answer that could work for a majority. If you are trying to motivate someone else then maybe praise them or take them out for dinner or something to make them feel happy they did so, or 'motivated'. Of course, "what about those who do not have friends, family, or normal human contact?" Now in that case this makes this much more harder. I guess theres not much more you can do other than, educated them in school about the consequences and rewards of working long term, and short term, or advertising the good about working.