Motivation MIA? These five culprits may be to blame. We can help you overcome them.

Woman running on a track
Credit: Brooke Schaal Photography/Getty Images

You've committed to a new gym routine and cleaned up your diet (go you!), and for days-even weeks-you're brimming over with eagerness. You're excited to wake up early to meet with your trainer, you look forward to every fresh-tasting lunch or snack you've packed for the day. Then suddenly-poof-it's gone. You wake up one day dreading your workout. The siren call of the McDonald's you pass on the way to work is almost too much to bear.

Sometimes, regular old stress or fatigue is to blame. But other times, something sneakier is at play. We asked David Gard, Ph.D., a professor of psychology at San Francisco State University, why motivation pulls a disappearing act-and how to find it again.

You Have Three Birthday Parties and a Bridal Shower This Weekend

Even if you love shopping, deciding what gifts to buy for all those events might have a surprising rebound effect-later your motivation to get off the couch and get to the gym might be nonexistent. "One thing people often don't realize is that making a number of small decisions can actually block your progress toward bigger choices," says Gard. "In other words, making a lot of little decisions-even to do things you enjoy-might deplete your motivation to put your gym shoes on later."

Get motivated: This is one reason why some experts say that people who work out in the morning tend to be more consistent-they haven't had a chance to make tons of choices and deplete their drive. We have 7 Steps to Becoming a Morning Exerciser.

You're In a Rut

You know how you switch up your shampoo and conditioner periodically because your old type just stops working? It's the same with other routines, Gard says. "Your body can adjust in some way to an exercise routine or new diet, and you may need to make changes," he explains. Just because a particular motivator or training plan has worked for you for the past six months doesn't mean it will necessarily work for you tomorrow morning, says Gard.

Get motivated: If you feel like you're backsliding, reassess your plan and switch things up. If you're feeling bored of your gym routine, consider trying a new class that emphasizes a mind-body connection, like yoga (there are so.many.types.). Psst: Athleta’s Elation Ice Dye 7/8 Tight in Powervita are quick-drying and slightly compressive, which means you can focus on what really matters, striking mindfulness through a new practice.

You're Too Focused On the Big Picture

The more you obsess over your end goal of running a marathon, the harder you may find it to actually lace up your shoes in the morning. That's because each big goal is actually made up of hundreds of much smaller mini-goals-the decision to get up early, to get dressed in gym clothes, to head out the door on your run. Breaking your goals down into smaller steps can rev your drive. "Focusing too much on big goals can be more daunting; at some point, you may not be able to see the light at the end of the tunnel. But with smaller goals, you constantly see progress, which is motivating," says Gard. (Related: 15 Super-Small Diet Changes for Weight Loss)

Get motivated: Take your overarching goal, and break it down to its smallest, most specific parts. What's the first actual action you need to take to start chasing that goal? For example, if you want to become a vegetarian, maybe your first steps are using up all the meat that's left in your fridge, looking up meat-free recipes, then printing out those recipes. Think tiny.

You're Not Making It Fun

Sometimes, even the smaller goals you set for yourself can seem overwhelming or even just boring. And when you start to dread taking the steps you have to take to reach a goal, it's natural to find that your motivation is waning.

Get motivated: Rather than just trying to force yourself to take healthy steps, try pairing your mini goals with things you find inherently enjoyable, Gard says. Meaning, turn on your favorite podcast before attempting to get into your gym clothes. "Pairing something positive with something you need to do gives you a burst of something to look forward to and focus on, which is naturally motivating," he explains.

You're Being Too Private

"Not sharing your goals or progress with people can make it easy to quit," Gard notes. Saying out loud what you're trying to work on is a good way of boost your accountability, encouraging you to keep striving toward the goal.

Get motivated: Tell your friends what your plans are. ("I'm quitting meat for August!") Or post about it on social media. But commit to posting on a set schedule, or else you may let yourself peter out. (See more: 10 Reasons Your Workout Should Include Your Friends)