Manage your emotions

Emotions can ruin your day, and subsequently any healthy progress you've made, Teeter warns. One bad day at work can lead to binge eating and drinking in front of the TV instead of preparing a nourishing meal and hitting the gym. When you're feeling bad, Teeter recommends paying attention to why you feel that way so you can comfort yourself in a more productive way, instead of stuffing yourself full of food until you can't move.

Focus on feeling better, rather than what you see in the mirror

Sometimes "looking good in a bathing suit" isn't a big enough goal, at least not if you want to keep the weight off for longer than the warm summer months. "It's important to establish the reason why you want to get healthy. Maybe it's for your kids or grandkids," Byers suggests. "Maybe you want to get healthy so you can have a family. No matter where you are in your journey, I encourage you to think about your personal 'why' and post it on a vision board where you can see it every day."

Track your progress with pictures

While it's important to focus on how you feel over how you look, Byers also suggests taking pictures every week so you can visually track your progress. On a day-to-day basis, you might not notice the changes that a photo will capture. "The scale can be misleading -- it doesn't know if you're replacing fat with muscle," notes Byers. "The more muscle you have, the more toned you look as long as your nutrition is on point."

Don't eat or drink anything handed to you through a window

Yes, even coffee. Get up and go inside to get your coffee if you want it that bad, Marie suggests. Better yet, go someplace where you can control how much sugar and cream goes into it.

Step outside your comfort zone

Embrace uncertainty, especially if you consider yourself a perfectionist. "Things will not always go your way, no matter how prepared you think you are," Teeter says. "Many folks throw in the towel after just one setback. But if you condition yourself to expect and embrace [setbacks], you'll be far happier with yourself and the progress you're making -- even during the difficult times."

Eat a lean protein and complex carb during each meal

For Byers, that meant lots of grilled chicken with sweet potatoes, grilled zucchini with asparagus, and meal-replacement shakes. "One of my favorite meals is scrambled egg whites with hash browns and green salsa mixed together," she says. "Another favorite is extra-lean turkey tacos on corn tortillas and avocado slices, plus salsa."

Start today

The sooner you start, the sooner you'll see results: "There will always be reasons to start tomorrow, or wait until your busy season is over," Lehman adds. "Fight through your excuses and do something right now."