If you are asking about altitude acclimatization with your "hilly regions" mention, the only way to train is to exercise at higher altitude. There is no magic bullet. That is why climbing expeditions often walk for a couple of weeks to reach base camp, to allow their lungs time to adjust to lower oxygen levels.
Depending on where home is, you can spend time in nearby mountains hiking the trails, etc to start building your lungs. Walking up stairs in multi-story buildings also helps build your lungs strength. But even with this, you will still be oxygen starved when you first reach higher altitudes, so will be winded and more tired then you expect.