Looking for examples in the present time where the core belief isn't true? For example, if you don't believe you have a sense of humor and catch yourself laughing; the more you catch yourself laughing and/or actual work at it, the more the seesaw of belief will tip the other way?

If you "know" it is incorrect; just kept telling yourself the opposite? I use to do that, when my T or husband (people whom I trust) told me something about myself I did not believe. It works kind of the same way; you tell yourself you have a good sense of humor and you will notice when it comes into play and eventually the weight of that evidence will change the balance of belief.