I echo others' advice here, Dum, especially re learning more about the health/long-term benefits of low carbing. That was a real lightbulb moment for me, and it's what enables me to stick with it for most of the time.
Like everyone, though, I'm only human and there are times when I stray off plan. Sometimes it's circumstances. For example, I travel a fair bit for work, and I can't always control what food will be available to eat. Going to Vietnam earlier in the year was a good example. I could have had a low carb meal in the hotel every night, but I wanted to be able to eat genuine Vietnamese food. So I did - and I enjoyed it thoroughly. Sometimes, for example, you get invited out to dinner, and the menu will be carb-laden. But it would be very rude to not eat the food that's been cooked for you! (Even when I've been able to let my host/hostess know that I'm low carbing, it's still not unusual to be given something carby, simply because people often don't understand what is or isn't carby!)
But after these moments, my life is usually a pretty low carb one - certainly relative to 'normal' diets. I very, very, very rarely eat pasta or rice or bread. I don't eat much fruit; if I do it's lower carb fruit like rhubarb, which I love - but have to use an artificial sweetener to make it palatable, so I avoid this too, even though I love it!
My downfall is white wine, which I'm trying to restrict as much as possible.
What really cemented me to this way of life and eating was reading more about it. "Escape the Diet Trap" by Dr John Briffa was the first book I read, and it was a real epiphany for me.
I followed that by "The Diet Delusion" by Gary Taubes. A much harder-going book, but incredibly thorough. Followed by his more palatable "Why We Get Fat, and What to Do About It".
Finding out that a high carb diet is associated not just with weight gain but also obesity, hypertension, diabetes, cancer and Alzheimer's disease was a total shock. My gran was and my dad is a Type 2 diabetic (my dad now has to have insulin as well, as it's not well-controlled), and my mum died from advanced breast cancer, so these are obviously things I'm very aware of.
I'm also older than many on Mumsnet; I started this palaver aged 52, (I'm now 55), when I suddenly became aware that not only was I overweight, with a weight that was creeping inexorably upwards, but I was also very unfit. So I also have a personal trainer who I see twice a week. I'ave just joined a new gym that will be running personal trainer-based classes, which I'm hoping to do at least once a week. I want to be fit and healthy in my later years, so that I can enjoy my retirement!
Very, very long post but a roundabout way of saying - read more about low carbing, and think beyond the 'diet' side of it.