Before you make your reservation, make sure the hotel has a fitness center. Pack for fitness. Take your exercise gear along - workout clothes, swim suit, athletic shoes, a skip rope. Stay active in the air. During a flight, get up and move around at least once each hour.
Some travelers even perform in-plane fitness routines.
Make the airport your gym. Instead of sitting around between flights, take a hike through the airport. Work in a workout. When you reach your hotel, keep moving. Take a walk to see the sights.