The beliefs that underlie this experience are that the body is an identity. This is like confusing the owner of a credit card with the actual plastic. In some ways the body is a badge or credit card, in that it is something you present to others to achieve credence. If there's a body there moving, it's a "person".
Choosing to identify with the body is probably originally motivated by an interest in, and later an addiction to, sensations which the body amplifies. As one grows more accustomed to living by those sensations they become habitual. Patterns of certainty grow up around the body which are much more solid and heavy than other certainties, of a mental or spiritual nature. Knocks on the skull, cut fingers and stubbed toes do their part to make it quite clear that this is reality and you had better listen to it if you know what's good for you. Add a few operations or childhood fevers and it can get quite solid and immutable -- you are your credit card, and don't dare budge beyond it. But the energy of the body itself is numb and unexciting energy. The perceptic frequencies are limited and somewhat dull without the addition of perceptics from nonbody source. Like a teenager who gets his very own AM radio for the first time, the owner can add excitement and responsive enthusiasm to what is essentially poor quality input. Imagining love, jumping to the rhythm, the teenager creates excitement and lays it on top of a fairly heavy, dull wave of the body (sound incoming). Most of us, but not all, outgrow AM music or at least later on buy better sets. Even the finest tuning and materials in a human body is lethargic in its own output, until some awareness and opinion comes along to hot it up. But a welltuned one is certainly easier to get going than one with imbalances and contradictions created into it.