Mitt work is one of the most important parts of boxing training. It's way more important than hitting the heavy bag which is all most aspiring boxers want to do. As a matter of fact a lot of advanced boxers and pros rarely even hit the heavy bag unless they're trainning specifically for a fight. That's because the bag will eat up your hands and wrists. Don't get me wrong, I love hitting the bag too (I'm pretty far from an advanced boxer, mind you) but the bag is dead. It just hangs there and takes punishment. One thing when hitting the heavy bag to remember is to move yourself around the bag. Use your footwork to move with the bag rather than reaching out between combinations to move the bag to where you want it. Try that with an opponent and you'll be eating a fist. Proper mitt work develops speed, timing and endurance and it's a more live training experience. If you can't get anyone in the gym to hold the mitts for you then buy some good ones of your own and have one of your kids or your wife or girlfriend hold them for you.