EA SPORTS Active 2

Besides the obvious cranking on workouts, there is a much easier... albeit defeatist way to complete this much faster.

Create a custom 1 hour workout with any of the exercises that don't use the sensor for tracking. The game won't allow for workouts longer than 1 hour or more than 50 exercises. Any of the Warm-ups or Cool Downs work as well as Push Ups, Star Planks, Straight Legged Sit-ups, Reverse Crunches, V Sit Crunches or anything else that requires you to be on the floor will work for this. I've found that if you want the max calorie count as well as time spent make a workout of 50 push ups. It will net you over 300 calories and take around 45 minutes. Repeat whichever workout you decide on until the achievement pops.

Of note... the game will not unlock achievements directly at the hour (or calorie) mark and generally require you to put in more effort. For a check to see how close you are to unlocking any particular achievement - in game, open Fitness Tools > My Milestones. There is a green bar for each milestone (there are more milestones than achievements) that shows progress toward particular goals.