The key to staying motivated is similar to fuel in a car—you don't need the motivation tank to be full to drive, you just need to prevent it from running empty, says Joshua C. Klapow, Ph.D., a clinical psychologist at the University of Alabama at Birmingham and author of Living SMART: 5 Essential Skills to Change Your Health Habits Forever. "I tell people not to waste precious time and energy on staying highly motivated because motivation has a natural rhythm. Most people see a drop in motivation as a signal of failure, but it's not," he says.
If you notice that your motivation is waning, give yourself a break from your diet or exercise plan for one to three days, Klapow says. "The problem with motivation is that the more people try to ‘catch' it, the more elusive it becomes; by allowing it to run its natural course and at the same time having a set of habit-changing skills (such as a meal plan for the week), you'll stay on track and your motivation levels will run their natural course."