There's a reason a "Missing Cat" flyer often has a reward on it: rewards motivate people to do things. In the case of teaching children, children often find motivation to learn when they are rewarded. In particular, tangible rewards can be better than simply saying, "This will help you in life." Tangible rewards can be things like giving out candy or other treats for correct answers or good behavior. As well, compliments and praise can acts as reward and motivation.
Games are fun, and can enliven a classroom. Plus, games can be educational. For example; put students in groups, and after each question asked, the first group to get the answer right wins a point. This can challenge them to work together to find the answer, as well as motivate them to think quickly and critically. Plus, it can be fun competition in the classroom. It's an easy way to wake up a sleepy classroom.
"Intrinsic motivation" is when a person does something because they want to, not because they were told. This is often more valuable for children. Giving them more say in the activities, or what book they want for the book review, can give them more motivation to do it. There certainly should be limits to what have a say in, but giving them choices can be a motivating way to fit with the overall plan and goals of the class.
Children, like adults, often need time to learn things. If they are rushed they are more likely to give up. Give them time to learn. As a teacher, don't feel you have to jump in right away if they haven't learned a topic. Let them explore and call upon their problem solving skills. When they see they can learn something without a lot of help, they feel more motivated and confident in their skills.