I've been working on "listening" to my pre-thoughts. It's interesting - once you catch it you automatically start translating it into words, or rethinking a thought "audibly"; it's very hard not to. Then I usually make fun of myself by pre-thinking "echo." On the downside, if you don't translate it into words it's vague and harder to remember - thinking with words is awesome.

For more concrete things you can also think about it with some sense - a touch, smell, sound, taste or sight that doesn't need words.