Updating training paces

Using the McMillan Running Calculator and using my last half marathon time for input I have a new set of pace times to start using in my training.  It always surprises me how much slower our training paces should be than what we are capable of. Especially for an endurance long run, which is supposed to be a low heart rate, easy conversational pace run.  According to the calculator I should run a 9:43 to 11:00 pace for my long runs.  I do believe I run too many of my days harder than I should, where they all start to slip in to stamina runs instead of endurance runs.   Well I plan to adhere to this set of paces for the next few months and see how things progress.