The process of motivation isn't a process that is nailed down in stone. There is variation among different methods; however, the processes are similar enough to generalize broad steps. Motivation generally begins with a need of some kind. Knowing that you have a need and are not obtaining it creates tension. That tension leads to the exploration of ways to fulfill the need which in turn leads to goal setting. With goals in place, work can begin to try and meet those goals and fulfill the need. Often, this requires behavior to change. Ideally, the end target is achieved, and the need is met. This would count as a reward, but I would be remiss not to at least mention that achieving a reward is not always the main motivation. Sometimes the motivation is to avoid a punishment. My soccer team knows that if they work hard during practice and run drills at 100% at "game speed," they won't have to do the sprints at the end of the practice. They are motivated to work hard to avoid a punishment. I suppose you could say that not doing the sprints is a reward too.
Any good manager knows how to motivate their employees, and rewards should constantly vary. This keeps things fresh for employees, but it also takes into account that the same reward doesn't work for every employee. Some employees might be motivated by increases in pay or bonuses. Some employees might be motivated by being offered an extra week of vacation time. Some employees might be motivated by being given certain work responsibilities. An employer would hopefully know his employees well enough to know which rewards work best for each employee or each situation.