As a Construction Manager, you will do just that: manage construction. You will be out in the field on a construction project but, you won't be hands-on per se. That means you won't be driving nails, turning bolts, pouring concrete, or welding structural members together. But, you will be getting your hands and boots dirty as you oversee the work, making sure it gets done according to spec and schedule, and ensuring materials and tools get to site when they are needed so that your crews aren't standing around and depleting your budget. It can be quite satisfying, especially when you're working with crews that take pride in their work. Overall, you may spend about 25% to 50% behind a desk or a meeting table as there are lots of meetings on a typical project!
Even though you would still have to do some desk time, I would suggest that you complement your construction management program with either a double major in mechanical or civil engineering. This will both broaden your scope of technical knowledge on an industrial construction project and distinguish you from the crowd of construction managers who focus on budgets, schedules and reporting. Good luck.