A reward is a thing given in recognition of one's service, effort, or achievement. I've learned that positive and negative reinforcement are very effective when it comes to changing a behavior or achieving a desirable behavior. Positive reinforcement is a reward for doing something well. Negative reinforcement is a penalty for not doing something. I practice this technique with my dog since he was a puppy. I always used positive reinforcement. For example, we trained him to pee in his pee pad, every time he does it we gave him treats (rewards) and every time he missed we let him stay in the corner for a couple minutes. After a few days, he learned how to pee in his pee pad and he never made a mess anymore. When our dog did something bad, we put him in the cage to lessen the behavior and this is an example of negative reinforcement. Rewards are very important to everyone because it is wonderful to feel that we accomplished something in life. Rewards give us the motivation to do better.
The Puzzle of Motivation - https://www.youtube.com/watch?v=rrkrvAUbU9Y
"The pleasure principle does not abandon the intention of ultimately obtaining pleasure, but it nevertheless demands and carries into effect the postponement of satisfaction, the abandonment of a number of possibilities of gaining satisfaction and the temporary toleration of unpleasure as a step on the long indirect road to pleasure" Sigmund Freud
"The consequences of an act affect the probability of it's occurring again" BF Skinner