When I first started I felt the same way. Playing barre chords was as much of a 'physical impossiblity' as is flying with a cape and a pair of tights.

I think the biggest problem with learning barre chords is the initial discomfort of laying your index finger across all the strings. Your finger isn't used to it, and you won't have any callouses where you're trying to press down.

But just keep at it, and all the practicing will pay off.