Training for a 1:20 half marathon. Last year I got 1:23:55. I’m currently doing 3x2 mile repeats at 6:00 pace. Is this too fast for this workout? If so, what should the pace be and how much rest between each one? I’m hoping to get to 5-6 of these repeats eventually. Do you also think this is a good workout for a half marathon? I appreciate the answers.