One way as I mentioned to get a nice workout is to take a nice long walk around the various terminals, or from one end to the other and back several times if it is smaller. If it's during the day, you'll end up avoiding the crowds and if it's at night, you'll have a clear path. This is one of my favorite ways to workout, especially if I'm traveling with someone.
If you are by yourself, or with someone, you can always focus on working your abs while sitting there. You can start with toe taps where you sit quite straight in your chair. Lift one foot just off the ground and hold it for 10 seconds before returning it to the floor, then lift the other food off the ground and hold for 10 seconds. Repeat until you have done 10 reps on each side and make sure you use your abdominal muscles as you do this exercise.
Next while sitting on the edge of the chair, lean your torso back, while holding the sides of the chair. Lift your legs out in front of you and then bring your knees up to your chest before extending out fully. Repeat until you've completed 15 repetitions. If that last exercise is a bit too hard, just raise your left leg, hold it up for 10 seconds before lowering it and then repeat with the right leg. Repeat the exercise until you've done it 10 times on each side.
Try a seated crunch by sitting up straight in the chair with your toes touching the ground and bring your hands behind your head. Slowly, bring your chest towards your lap and slowly back up. Repeat until you've done this chair crunch 15 times. Then you can also do a torso twist which is where you twist the torso to the left slowly as far as you can go, hold it, before twisting to the right and pausing. Continue until you've done 15 to 20 on each side.
If a torso twist is not enough, how about a seated bicycle crunch. Sit at the edge of the chair, lean your torso back to touch the back of the chair and place your hands behind your head. Now bring one elbow to the opposite knee by raising the leg off the ground , slowly, and then back, place the foot on the floor, then bring the other elbow to the opposite knee slowly. Repeat until you've completed 20 repetitions.
If it's not too crowed, perform either forward or backward lunges in a small area off the main walkways or in a corner. You'll need to do at least 10 on each side for the best results. If you are really dedicated, throw in a resistance band to do a few things off in the corner where it's not too crowded. Other ways to sneak in some exercising is to walk up stairs instead of using escalators, walk down the halls instead of moving sidewalks, and walk quickly between gates.
So if you travel a lot and still want to get a bit of a workout, I've outlined several ways you can do it without equipment. One word of advice is to travel in comfortable workout clothing so you can easily perform these exercises. Let me know what you think, I'd love to hear. Have a great day.