Chances are your lower legs and feet aren’t doing a whole lot when you’re in transit. One way to work those muscles is by doing calf and toe raises, which are just what they sound like. For a calf raise, keep the balls of your feet on the ground and lift your heels. You can lean on your knees or put your carry-on in your lap for extra resistance. Do 20 to 30 quick reps and switch to toe raises. For a toe raise, simply keep your heels planted and lift your toes in the same rapid succession. This will strengthen your ankle and shin muscles. Do two or three sets.