Here's a really excellent example of the kind of mitt holding we worked on in the day class. If you can tear your attention away from the cannon-like punches (seriously, it sounds like they're recording inside a battleship) take a moment to appreciate the coach. He's not doing anything complicated, but his position and rhythm are impeccable. Being good at mitt holding isn't calling out long sequences or fancy combinations, it's holding the mitts, and your body, in a way that compels the best performance out of your partner.