A workout routine doesn’t get more tired than when you do the same five—we’ll call them “classic”—exercises you’ve done since middle school phys ed class. And, TBH, in adulthood, it’s also likely the reason your fitness results have plateaued. Don’t know about you, but we’re always collectively on the lookout for a fun (and, OK, challenging) way to work on our fitness, specifically our abdominal muscles. That’s where Heather Andersen, the former ballerina turned Pilates instructor of the aptly named New York Pilates studio in SoHo, comes in. Let’s just say her method of core toning is just what we needed. And even though we’re not ones to give up our tried-and-true moves that easily, hers make it totally worth it.