It could be time to have a heart to heart with yourself. Look at the goal you set. Is that the most relevant goal you can have? Do you need to set a different goal? Are the steps to meet the goal what you need now to reach the goal? Is it time for professional help?
Working with a Certified Health Coach is a place to start. Their services range from goal-setting, nutrition, wellness, cheer leading, and helping with the mental aspects of your situation. Maybe the services of a personal trainer are in order. A visit to the nutritionist may kick-start your program again. One thing that is for certain, a bad diet can send any program into a death spiral.
The first answer will come to you as you look in the mirror and ask the above list of questions. Do it honestly and you'll be rewarded with at least a direction to follow. Next up is to take action.
I can't get you off the couch, to pick up the phone, or to get you to the gym. That has to come from you. So, go and get 'em. You can do it. You've had success in the past and now the thing is to get back to doing things that will bring you that success toward your goal.
My best to you as you go along your journey. If you have any questions for me, I can be reached at: firstname.lastname@example.org