For a full-body workout that will also help lift and tone your glutes, a mere 55-minute TRX class a few times a week will do the job. Founded a decade ago by a former Navy SEAL commando, TRX revolves around the use of suspension training equipment — which is a fancy way of saying straps that hang from the ceiling that you then use to perform exercises on. Though the goal of each class is to give your entire body a workout, your posterior is a big focus (after all, the glutes are your body's largest and quite possibly most powerful muscle group — and definitely the ones most relevant to that new pair of jeans). Classes are taught from 6 a.m. to 8 p.m., which makes coming up with an excuse to skip your workout "because there's not enough classes!" pretty much impossible.