Please motivate me, all you healthy superfit MNers!
OK, so I've got a stubborn BMI of 27.5, having put on three stone in the last two years or so (bloody Cerazette/sedentary office job). I'm tall, which is why my BMI isn't abysmal, but I really want to shift at least some of the flab by summer.
I've tried to lose it a few times since LAST summer by doing low-carbing, eating less with myfitnesspal, C25k etc, but just keep losing and gaining the same half stone or so whenever I inevitably surrender to a massive packet of jaffa cakes 
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I've never had to lose any significant amount of weight before, so I just don't understand how it's done, or really believe it's possible! I joined a gym last week and I've been trying out all the classes to see which ones I enjoy, for the first time ever, which I'm loving so far - but I know that, though it'll make me feel better and tone up a bit, this won't be enough on its own to see much weight loss. If I go to a class most days, and cut out the jaffa cakes and their evil junk food pals... will I actually lose weight? Is it possible?
Also hoping to get back on the C25k as soon as this damn ice thaws... I finished the programme but it's been a few weeks since I've braved the weather.
Please share your stories of weight loss success and reassure me that the effort I'm about to put in will not be all in vain! Also please tell me what it feels like to lose weight, any ups and downs I should prepare for, tips for 'digging deep' and just keeping going when comfort eating is calling... and if anyone's in the same position as me, join the club!