If you are using the Park Tool BBT-19, you can also use one of those big ass truck cross/t-wrench that has a 1 inch socket. The cross wrench will give you leverage on opposing sides of the tool and will prevent slipping and keeps you from having to push in constantly on the tool as Psimet stated. I don't know if you can get them at your local auto parts store, but I found one at a truck stop.