You'll need to earn all 50 badges in the game to earn this achievement. The majority of badges are earned by trying out a type of exercise for the first time, and by completing every session of a particular exercise. There are 23 different types of exercises, so you will earn 46 badges for completing them all.
You will also earn a badge for playing the game for three and ten days, and also for exercising for 30 and 60 minutes straight in one day. This adds four more, bringing the total to 50.
You can track the activity-specific badges by going into each exercise's section; the two for playing three and ten days are found on the far left of the main menu; and the 30 and 60 minute badges are found under My Progress.