I was never in the triple digit club, but I have been successfully maintaining a 50ish pound loss for over 6 years now so here's my input, for what it's worth

First the reality check-
The weight loss phase is the easy part, maintenance is where the work actually begins. This is because during the relatively short weight loss phase you're highly motivated. You're seeing a downward trend on the scale, you're fitting into new clothes, you're getting compliments, you're blood work/health conditions are improving etc etc. On the other hand-this all pretty much stops once you transition into maintenance and you lose those motivators that pushed you forward.

Instead there's 1.- 20, 30, 40+ years of 'real' life that's mostly 'same old, same old', mixed in with 2.- things like sickness, death of loved ones, injuries, holidays, job changes, moves, family dynamic changes (divorce, kids moving out, taking care of aging parents etc), vacations, stressful times, financial upsets etc etc. That combination leads to a 'perfect storm,' and it becomes very difficult to stay focused. And with loss of focus comes adherence failure.

And then throw into the mix all the old habits that you thought were gone that suddenly hit you from behind, when you're not paying attention/defenses are down, and it's a recipe for disaster, for most people. The long term success rate for weight loss management is absolutely dismal. BUT-there's a few of us statistical freaks of nature who are successfully maintaining and here's the good news-there's absolutely no reason why you, or anyone else reading this, cannot be a part of the 'elite' who are successful at this.

Second, the Plan-

-come up with your maintenance plan NOW, while you're still in the weight loss phase. It doesn't have to be super detailed, but write down some strategies that you'll be implementing on the day you hit your goal weight.

-along with a plan, always be working towards a new wellness goal-this is so important! It could be expanding your food horizons/learning how to cook new things, a new fitness goal, a new hobby or sport etc etc. It doesn't have to be something big-just a new focus that keeps your head in the game.

-be honest with yourself, always. My daily weigh-ins, that I keep on a trending app, make me be real with myself. You can do daily/weekly weigh-ins, or take measurements once a month etc-but have some sort of accountability tool that you use regularly, so you don't let a small blip become a large gain.

-realize that you'll have a maintenance range and not a set weight. Most people chose a 3lb-5lb range and this factors in normal weight fluctuations, small changes in exercise/routine, seasonal changes etc. Keep your eye on this range-it's your focal point. If/when you start creeping out of it, then you know it's time to make some small adjustments to get things back into that range. There's no need to panic when this happens, because you have a plan in place-you just need to get back to it with a bit more focus and then move on.

-realize that you will need to make adjustments as you go along and that's ok! Be open to being flexible and realize that you don't have to be perfect, you just have to be consistent most of the time. There will be times that you go off your plan and that's ok. The important thing is to keep these moments structured as much as possible. There's nothing wrong with giving yourself some grace when the difficult times hit or you're on vacation, or it's your birthday, but don't use these times as an excuse to completely fall away from your maintenance plan. In a nutshell-be an adult and take responsibility and get done what needs to get done