I fell off the fitness wagon after reaching my goals. Here's how I'm getting back on track.

Hitting a major goal or completing a long-term project brings with it a tremendous sense of satisfaction, as well as an almost inevitable letdown. You put your all into something, but what happens when that sense of urgency is gone or life gets in the way once you let your guard down?

On February 1, 2018, I completed my year-long project to adhere to the federal Physical Activity Guidelines and Dietary Guidelines with the support of the Science & Research Team of the American Council on Exercise (ACE).

I woke that morning elated about having finished a task that had become my driving focus each and every day for the previous year. I had achieved a level of health and fitness that seemed extremely unlikely just 12 months earlier. And I had learned to live a life that made me not only healthier and more active, but genuinely happier.

I was thrilled.

I was also ready for a break.

The physical effort involved in the project left me drained. For a year, I recorded every minute of physical activity. I logged every piece of fruit and cup of dairy. I tracked the color of every veggie I ate. While I certainly planned on maintaining a healthy nutrition and physical-activity program going forward, I simply needed a break from being so exacting and disciplined in every aspect of my lifestyle.

My plan was to continue following the rules I had learned, but to prepare my food without a kitchen scale or measuring cup in sight — and maybe visit a few restaurants that I had been avoiding.

I also wanted to maintain the fitness regimen that had kept me progressing (and pain-free) for the previous year. That said, I would give myself some leeway to skip a workout here or there.

One month of loosening the reigns and then I’d get back on track and regain the discipline that allowed my success in the first place. That was the plan.

But you know what they say about plans.

On literally the last night of that month, as my wife and I were getting ready for bed, our son yelled from downstairs, “Do you guys hear water running?”

By the time we found the leaking pipe and turned the water off, water had destroyed an entire bathroom and the carpet on the second floor, and had run through the ceiling and walls enough to destroy most of the kitchen and the hardwood on the first floor.

To make a long, painful story short, after spending more than 40 of the next 60 nights in a hotel, my eating habits were as much of a wreck as my house, and my workout routine had been completely dismantled.

That’s how I found myself only 90 days removed from one of the biggest achievements of my life, 8 or 10 pounds heavier and decidedly off track.

So now what?

No matter why you may have lapsed in your efforts, whether it was illness, injury or the plumbing gods sending a flood to mock your best-laid plans, there are strategies you can use to get back on top of your game.

Remember that You’ve Been Successful Before

One of the best predictors of a person’s ability to adhere to a nutrition plan or physical-activity program in the future is having done so successfully in the past. Fortunately, I have a lot of knowledge and experience to fall back on.

I now not only know what I need to do to change my lifestyle, but I also have recent experience in establishing and maintaining the habits required for success.

The biggest difference between the current me and the version of me from just 15 months ago is this: I know what to do. And I know that I can do it.

Reach out to Your Support Network

Another predictor of adherence to lifestyle change is the presence of a reliable social-support network. I reached out to those people who helped me the first time around and re-enlisted their support. I talked to my wife about cooking healthier dinners and buying fewer high-sugar snacks, and I called my hiking partners to set up a schedule to hit the trails at least once a week.

If you find yourself in the same situation, think about the people who positively influenced your efforts and make them aware that you could use their help in recommitting to a healthy lifestyle.

Reestablish Old Habits, but Start Slowly

As I write this, I’ve been back in my home for about two weeks. I’m easing back into my workout routine and eating much healthier. I’ve gone for a few hikes and have been taking the dog for a couple of walks each day. I’m feeling better already and am looking forward to reestablishing the important habits that I had let slip.

You might feel a drive, as I did, to pick up right where you left off. However, that might prove to be a mistake, as you don’t want to push yourself too far too soon. Be patient, but persistent.

I know you can do it.

I’m honored that NBC News BETTER invited me to share my journey with you through the completion of The Lifestyle Project and beyond, and now I want to hear from you. Do you have any strategies to share that helped you get back on track after some time off? Tell me about them. Have questions about my journey? Ask me on Twitter or follow me on Instagram.

MORE FROM DANIEL J. GREEN'S INSPIRING WEIGHT LOSS JOURNEY

• 'I'm an overweight health editor and I'm finally taking my own advice'
• What 5 months of consistent, healthy weight loss looks like
• Why I'm reconsidering the idea of 'ideal weight'
• Why losing weight has nothing to do with the scale