My first serious venture was in 1995. I was 19 years old and had spent all of my teenage years obese (I was 250-275 as a 14 year old and pretty much stayed in that range throughout high school). That was back during the phentermine craze; my mom drove me over 60 miles away every month to visit a weight-loss specialty clinic that handed out phentermine like it was candy. I went down to 220 before my anxieties became really bad and life pretty much got in the way; my mom became terminally ill with cancer and we temporarily moved out of state to stay with my grandmother. I was no longer able to visit the clinic for the meds and was obviously extremely stressed over watching my mom die (we couldn't hire a nurse so I was the one taking care of her all around the clock), and the weight piled right back on. I even tried revisiting the clinic and going back on the meds after I returned home but it never really clicked for me again.
My next serious venture was back in 2000. I'm not sure anymore what triggered me to start losing weight that time, but I do remember that I was all about low-fat and ate so little for an extended period of time that I nearly ended up in the hospital. I burned myself out completely when I reached 220, and coupled with not being able to handle the attention a smaller body was giving me, I gave up (it took me years to be able to form healthy, normal relationships due to being sexually abused as a child). And once again, the weight piled back on. And a few years later when I had my first boyfriend and moved out of state with him, I gained another 100 on top of where I already was!

But that's a whole other story.
My dad passed away in early 2004 (another obviously stressful period of my life) when I was at my highest weight ever. I was completely miserable in all aspects of my life. Sometime toward the end of the year, I stepped on the scale with a big sigh. Seeing myself that far above 300 pounds was outright painful, but at least I was no longer in denial. I told myself there was no use crying over spilled milkshake and completely overhauled the way I was eating. I also took advantage of my free YMCA membership (I was an employee at the time). It has taken me years to clean up my life, and not just the issues with my weight. I've learned a lot about myself over the years with what works and what doesn't, and when I haven't been actively losing I've at least been maintaining (aside from last winter, which I've since corrected). I've had to learn more constructive ways to deal with my many issues; I also had to learn to value and take care of myself in all aspects.
The year 2006 was a huge transition for me. I broke off the abusive relationship I'd felt trapped in and started a long-distance relationship with a wonderful someone I'd befriended online the year before. After working hard to save up to move across the country, I moved in with him in late 2007. At the time I'd been maintaining at 285. I stayed in maintenance mode while adjusting to everything until sometime in 2009 when I decided it was time to get cracking yet again. Sigh . . . although we didn't have immediate plans I knew we'd eventually get married and I didn't want to be the fat bride. I fought my way down to about 255 by the time we got married in 2010, and I stayed in that range for quite a while. I did manage to get down to around 235 last year, but that was the winter all sorts of stress got thrown my way with my car being broken down for months, dealing with extreme family issues back in my home state, getting pregnant for the first time, and having a miscarriage in January. I found myself back up at 267 and said no more. Whatever happens in my life, I can't let my weight and health take a back seat! So I got back to serious work.
I'm currently less than ten pounds away from that 220 low point I've only managed to get down to twice. I think I'm in a different place this time, both mentally and physically. Back in those days, I'd lost only 30-40 pounds before burning out. This time, I've already lost 130 and have a much better idea about the personal needs of my body and the required perseverance. I know now that low-fat doesn't work for me, but that reducing simple carbs and watching overall portions does. I also keep a physical food/fitness journal to track my progress. My hunger is under control by this method, and my various anxieties are more under check. I feel calm and relaxed, unlike last winter when it simply wasn't happening fast enough and I threw a fit before throwing in the towel.
I do worry a bit about getting below this magical number of 220 since it's where I've always failed. But I'm in a better place this time around and I think I'm finally going to make it happen.
