Barre chords are the magic that I can't comprehend. I see people barre those three strings and I can't figure out how to do that and play the chord cleanly.
There's not really any magic to it. Just keep doing it, and after a while it'll start to sound right. And eventually the pain mostly goes away.
I can barre some chords but barring in the A major pattern is rough. Then my guitarist said "no one does it that way" and he showed me you press the three strings with your third finger while kind of hyperextending the joint...but my finger doesn't work that way!