People often ask us how we manage to continue our travels for extended periods. If you're not familiar with our story, in 2011 we quit our jobs, sold our house, and gave away most of our possessions to travel around the world for what we thought would be a year. However, after learning to live much more simply on the road, we have stretched our career break into a lifestyle change and are still traveling full-time. The key to long-term travel is keeping costs down and approaching the journey differently from the way you might that annual one- or two-week vacation.

When we left Philadelphia on our yearlong odyssey, we budgeted for lodging the same way we had in the past for a 10-day vacation in Europe, i.e. approximately $100 a night for a quaint B&B or a small city hotel. In Asia, we soon realized this was necessary in major cities like Shanghai and Hong Kong; other travelers we met in places like Thailand and Malaysia were faring quite well on $30 or $40 a night.

This opened our eyes to the fact that our notion of how much traveling costs had been skewed by our trips to Europe and, quite frankly, living in a region of America that is more expensive than average. We dropped our budget to $50 per night, and for the last four years on the road have been able to beat even that. For long-term travelers, there are a few tips we offer to keep lodging costs down:

Stay in an apartment rental, where the cost is less than a hotel. This option will also lower your food costs because you can prepare many of your own meals. Our favorite companies are Airbnb, HomeAway, VRBO, and Sabbatical Homes.

Stay at a single destination to get a long-term rental discount. Weekly and monthly rates offer significant savings - sometimes 50 percent - off nightly rates.

Consider cheaper destinations. We find there is something interesting to see and do just about anywhere in the world. Southeast Asia is exceptionally inexpensive; our best deal was a modern, charming hotel in Hue, Vietnam, where a very comfortable room with private bath, WiFi, and breakfast cost $22 per night! Lately, we've discovered wonderful values and magnificent sights in southeastern European countries like Romania and Slovenia. Better yet, these places are still untouched by mass tourism.

Long-term travel is possible by setting a realistic budget and sticking to it. In the next few weeks, we'll cover other ways to save on expenses.

Larissa and Michael Milne are the authors of "Philadelphia Liberty Trail," a guidebook to the city's historic district.