You may not believe me, but I've never tried ...
You may not believe this, but I've never been to ...
This may seem hard to believe, but I've never liked ...
This may seem hard to believe, but I've been to ...
You won't believe this, but I've just ...
I know it's hard to believe, but I've never ...
As amazing as it sounds, I haven't seen ... yet.
You'll never believe this, but I've always liked ...
This may sound unbelievable, but I've ...