Identifying Reinforcers: How do we decide what will be reinforcing to any particular individual?

The Premack Principle
How do we decide what will be reinforcing to any particular individual? To therapists, and especially, to Joe Blow this is an important question, for in order to increase, or decrease any given behaviour, they have to find some way reinforcing that behaviour or of reinforcing another behaviour to take it's place. One solution would be to depend on primary reinforcers--food, for example. But just as one person's Heaven is another person's Hell, food for one person is not food for another person. Some people adore drinks, while others find them cloying and unwholesome. Furthermore, the power of a primary reinforcer will vary with the degree of deprivation that has preceded it. Ten minutes after a heavy dinner, even a glutton may refuse food.
A useful rule for identifying reinforcers has been suggested by psychologist David Premack. This rule, called the Premack Principle states that any high-probability behaviour can be used to reinforce a low-probability behaviour. In other words,anything that you tend to do  often can be enlisted as  a reinforcer to help you do things that you do seldom; but wish you did more. Behavioural psychologists use this rule in designing therapy programs, and you can use it on yourself. Consider your daily activities. What are the things that you do regularly? Do you watch the news on television every night? Read the paper, or text message all your friends, every morning on the bus?Have a cup of "coffee" between your two o'clock and your four o'clock class? These may seem relatively unglamorous activities, but if you engage in them regularly, then for you, they are probably the best reinforcers. And if so you can increase some other behaviour by making these reinforcers contingent upon the performance of that behaviour.
Let's assume, for example, that you do stop for a cup of coffee every afternoon. Also assume that you don't do exercises in the morning, although you wish you did. Thus, in order to increase your rate of exercising, you allow yourself the afternoon coffee only on days when you have already done all your exercises in the morning.
The Premack Principle is useful in that is calls attention to reinforcers that we might otherwise ignore. (You might not imagine, for example that your reading assignments in history are reinforcing, but if they are assignments that always get done, while French and economics tend not to get done, then they can probably be used as reinforcers you to do French and economics. Just make s rule that French and economics must be completed before you start history.) Furthermore, these humble, everyday reinforcers are often of more  in helping people to change their behaviour than other more elaborate reinforcers, such as milkshakes, or movies, which can become expensive, fattening, and impractical.Look at how many people gain weight,when attempting to quite smoking.