Naturally thin people are often in motion. Whether they’re playing with the dog, walking to the store or doing housework, you will rarely find a thin person sitting. Find ways to incorporate more movement into your day. If you’re not sure what your current activity level is, buy a pedometer and record the number of steps you take daily. Once you have a baseline, work hard to increase your walking by 500 steps per week until you reach 10,000 steps per day.