“The ‘drawing-in maneuver’ is a great exercise to engage the innermost core muscles, called the transverse abdominis,” says Zetlin. And it also happens to be easy to do whether you’re sitting in traffic or wedged into coach. Sit straight up and take a breath, making sure your glutes and core are engaged. Breathe out through your nose while drawing your abdominals up and in, so that it feels like your bellybutton is touching your spine. Hold this for twenty seconds while continuing to breathe through your nose, then release. Do three sets with a few seconds rest in between.