Something to add to the walking/cardio is a simple little instrument called the ab wheel or ab roller. These are available at Wal-Mart or most any other store that carries exercise equipment. They take up very little space - about the same as a shoe box, especially good for the abs, also lower back and upper body/shoulders and can be used in the hotel room, back of the truck, anywhere there's six feet of space. One note of caution: not for you if you've got pre-existing shoulder or lower back problems.