The Biggest Loser Ultimate Workout

Set up a 12 week exercise routine and make sure you complete all your scheduled exercises for the 12 weeks. If you miss any scheduled routines simply adjust your clock in your system settings to the missed date and play.

This achievement does not require you to complete any Health & Lifestyle tasks.

I think the minimum is 2 routines a week for 10 minutes. If you can't be bothered I'm certain you can start the routine then walk away for 10 minutes until it's over. If you want to get it out of the way quickly you could change your system clock and repeat the process.