In essence, people can think visually, kinetically (feeling), aurally (sound).
Most folks imagine with pictures, but many don't. You are not alone.
For example: I'm sure you can imagine what it felt like when something really funny happened to you, right? And you could probably also remember listening to a song you heard on the radio. Now - recall what it felt like when you were on a beach (or a snowy mountain), and recall what it sounded like. If you cannot remember, imagine the feeling of the sun, sound and imagine the sound you might hear.