With the first official weekend of summer upon us, it’s time for one last-ditch effort to get that body bathing-suit ready — which means saying goodbye to those half-hearted treadmill sessions and pathetic attempts at crunches.

“The goal is to shock your body into seeing results,” says Ian Andracchio, owner of Center City’s RowZone, which specializes in calorie-torching, on-dry-land rowing classes that blast through almost 700 calories an hour. The daily 45-minute, full-body workouts work your legs, back, chest and arms — the same areas you (try to) exercise running, doing squats and lifting weights, except you'll see results quickly, so you can feel good about showing some skin down the Shore. Even better, zero impact on those ankles and knees means rowing is a great way for anyone from teens to 60-somethings to build strength and endurance.

Of course, while gaining endurance and scoring a rock-hard core, don’t be surprised if you pick up a few new friends, too. “It’s very social,” Andracchio says about the community feel that RowZone calls the “Crew Effect.” “Everybody knows each other.” Something that happens easily, when you’re “racing” your fellow classmates. There are even classes that teach proper “on the river” technique and form so you'll be ready for your regatta debut. Some boat teams even train at RowZone when the Schuylkill is frozen over.

So before donning that skimpy little bikini or baring your wimpy chest, sign up for a few classes. (The first class is free, and memberships are available.) The effort will be well worth it when your summer crush asks if you want to hit the beach.