How many times did you "relapse" before you finally kept the weight off long term?

I think I joined in 2011 and didn't get serious until 2014. Many failure and crash diets in between. You just have to decide when the right time I for you and go with a plan that will suit you for life.

Well if you count fad diets like Atkins/Keto I started those at least 3-4 times and never kept weight off for more than a few months before reverting to old ways. Once I understood the energy balance though, none. It's been since 2013 and I occasionally stop tracking and yolo my way up 10lbs or so but I know how to fix it and I do it qute easily. I don't think 10lbs up or down is considered yo-yoing so I'm okay with that as a buffer to signal me to get my kitten together

Once, 18 years ago... but it took me 14 years to be 100% committed. I joined MFP 5 years ago and been maintaining for almost 3 years now.

Ask yourself why you fail. There's a good chance that whatever change you're doing is just not sustainable for you... find something that is.

Many times. I was down to a reasonable "goal weight" (down 65 lbs) and gained over 80 back before I even thought about what maintenance would mean. Since then I did the lose 10 gain 10 over and over.
When did it click?
When I finally realized there was a lot more to it than just being a lighter weight ASAP. When I realized I didn't HAVE to lose the weight all in one shot. I started thinking more about how I should be managing my weight, not just how to lose the most. (This was my mindset losing it the first time, and unfortunately lead me to gaining it back just as quickly.)
I eat more than before when I am actively trying to lose now, and I am still consistent with tracking even when I'm not. I found something to keep me active whether I'm losing/maintaining/frustrated with myself (lifting).
I'm down over 35 lbs from my heaviest currently, and although it's taken longer I feel much more accomplished than I did even getting to my lowest weight the first time.

My weight loss chart looks like a heartbeat. I've never been overweight, but I always seem to go up and down between 140lbs - 160lbs. Really hoping this time it'll stick, I want to get back into the 130s! I always seem to fall off the wagon during the winter.

I completely sympathize with you. That's exactly where I am right now.

A few years ago, I weighed in at 178 pounds, which was the most I have ever weighed. I was already in a terrible state of mind because I wasn't happy with my job and I just ended a pretty wretched relationship, so add that extra weight into all of that, and I was feeling pretty miserable with myself. But that was when I took control of my weight and started running. I lost 18 pounds. I had tears in my eyes when I stood on the scale and saw that I weighed 160 - my lightest weight in years.

But lately, I've been stressed out with grad school and buying a new house, and working out was the first thing to go. I also wasn't paying attention to my diet, and I was cheating far too much. When I stood on the scale on Tuesday, I weighed 171 pounds and I wanted to cry. I spent the entire yoga class trying to calm down because I was so mad at myself. Yes, I know how I got to that weight, and I know how to fix it. But I was frustrated that I had to lose all of that weight again and then keep pushing to my goal weight.

As sllm1 said, I think the biggest thing is forgiving yourself for losing focus, and then to keep pushing forward. We can do this!

I was lose 5-10 and give up many times over the years. Finally I got it right, I guess. What was different? I started paying attention to my activity, moving more. And maybe was just ready. As I understood calorie counting, food logging and whatnot before. But would still fall off track after a few weeks.

Maybe also the 'technology' of being able to log by phone? I did not have that 5 years ago. (Was end of 2013 that I got started, and then in 2014 successfully reached maintenance.)