The fitness wake-up call can be a powerful catalyst for change. For Matthew Richter-Sand, it came during a flight home to see his family.

When the flight hit some turbulence, the 30-year-old felt his belly fat bouncing up and down along with the plane. "I was so disgusted; (being obese) wasn’t me," said Richter-Sand of Los Angeles. "Right then and there, I swore to change."

Establishing new fitness habits isn’t easy, but as Richter-Sand quickly learned, it’s the key to success. Habits — unlike resolutions — last. The behaviors become wired so deeply into our brains that they occur without thinking, possibly freeing up the old noodle for other matters. And though habits take longer to establish and change, they are worth the patience and work.

Researchers still debate the time it takes for a behavior to become an ingrained action, but some findings show it takes four to six weeks of "consistent" action, said sports psychologist Gregory Chertok of the Physical Medicine and Rehabilitation Center in New Jersey.

For Richter-Sand, it took about two months before his workout pattern felt automatic. "In the beginning, I did what most people do; I overcompensated," he said. "I tried to change everything at once, which is a disaster."

Making lasting change involves going through stages that aren’t necessarily linear, said Chertok. People fluctuate and transition between the stages. Knowing how to move through them can get you where you want to be. Here, we take a look at the stages:

NOT READY TO CHANGE

Looks like: You might be unaware your behavior is causing problems. Unfortunately, "pre-contemplation is where most people are at, with regard to lifestyle changes," said Lisa Menninger, a Utah-based wellness consultant. You may be aware that doing things differently could be beneficial, but there is resistance. This is where people tell themselves: "It’s going to be hard. It’s going to take too much time. It’s going to hurt," Menninger said.

Get through it: She often tells people stuck in this stage that if they avoid discomfort now, it will only get worse and become chronic.

"This can at least get the wheels turning and help them into the next stage. It doesn’t require they do anything, except merely consider this reality," she said.

CONTEMPLATING CHANGE

Looks like: You’re considering change, looking at the pros and cons, perhaps because, like Richter-Sands, you’ve had your wake-up call. You’re not actually doing anything yet, but you think it might be a good idea.

Get through it: Mental images are good here. Visualization — or writing something down on paper — can also reprogram the neural circuitry of the brain, which has a direct impact on performance, said Chertok. "Think about how your life will look if you don’t change," he said. "Then visualize the types of clothes you’ll be wearing, how you’ll feel when looking in a mirror, the response you get from your partner or children when you do," he said.

PREPARING TO CHANGE

Looks like: You’re building momentum by setting small goals — making the appointment with the trainer, getting the gym membership, buying equipment or enlisting someone or something to help you track your progress.

Get through it: "The accountability factor is really important," said Gina Lombardi, a spokeswoman for the National Strength and Conditioning Association. The right person is key. It could be a certified personal trainer or wellness consultant or a coach. It can even be a friend who works out regularly, but make sure you find the right fit, said Menninger. "The trainer needs to meet the client where he or she is, striking the right balance between setting and meeting challenges."

CHANGING

Looks like: You’re doing something! In the action stage, new healthy behaviors have been established; the tricky part is sticking to them. If you have accountability — it should be more painful to skip your habit than to actually do it — and you remember why you want to change, you’ll have more success in this stage.

Get through it: A common mistake, however, is doing too much too soon, or getting injured because people think they’re in better shape than they are. Richter-Sand, an Air Force veteran, worked out so hard that two days after he started, he couldn’t get out of bed. "It was a science experiment," he said. "I had to find the right things that worked for me."

Have family and friends help you avoid tempting places, such as restaurants, and get to bed on time, Chertok suggested. "Sustained change sometimes requires the guidance of somebody with pre-existing healthy behaviors," said Chertok.

Also, start keeping a food log, said Menninger. The right food will help keep the workouts going; if you’re eating poorly, you won’t have enough fuel.

Julie Raines, 52, of Winston-Salem, N.C., maintains her fitness habits by making her workouts fun and setting goals for events ranging from charity bike rides to triathlons and half marathons. When she first joined the YMCA, her fitness trainer set her up on the FitLinxx system, which gave her points-based weight-lifting and aerobic activities. "Seeing my progress even just in terms of activity helped to motivate me and establish fitness as a habit," she said. "Later, tracking my workouts using a Garmin and heart rate monitor was useful in motivating me."

KEEPING UP A NEW HABIT

Looks like: After six months of sustained change, you’ve hit the "maintenance" phase. It’s still easy to slip, but "if you’ve changed lifestyle habits for yourself, rather than doing something because you ‘have to,’ this stage is easier," said Menninger. "It’s shifting from ‘I have to’ to ‘I want to.’"

Get through it: If it feels weird to do things for your own benefit, remind yourself that you want to have options as you age, said Menninger. Without health and strength, you’ll have to make compromises and you’ll limit yourself, she said. "When we’re clear on why we are doing what we are doing, we will stick with it — for good."

Raines now sees fitness as a hobby. "So it’s not just a habit, it’s a pastime," she said.

And Richter-Sand, now a personal trainer who runs an online nutrition and fitness company, found that his habit was more sustainable when he stopped trying things that worked for others. "There’s no silver bullet — you have to experiment and see what works for you," he said. "It’s taken me two to three years to where I feel good about where I am. And I’m still learning."