You have taken a vital first step right here on this forum by telling friends about your goals and even sharing photos. This puts pressure on you to live up to your goals. Most people will let themselves down quietly before being embarrassed by it when others know. Don't know your situation but I know I wouldn't stand a chance without a gym membership. Cold weather not a factor inside the gym. Most people make radical changes like crash diets that they cannot sustain for the long haul. This is a mistake. Yes you always want to drop weight fast but the main thing is that the weight stay off. This is done with a lifestyle change that you can live with. You must indulge in s few things you love as a reward for cleaning up the majority of your bad habits. This doesn't mean the all you can eat buffet but you dont have to eat like a rabbit the rest of your life either. Pick your favorite unhealthy food or drink and make that the reward for doing the right thing the rest of the week. My weakness is beer. I would rather drink the calories than eat them. I have some beer on the weekend and during the week I watch my portions and eat something healthy. I am at the gym four nights a week for about 75-90 minutes. I am not ripped because of the beer and I know that but I wouldn't be happy with out some import brew. So I sacrifice my ab six pack for some imported six packs and its all good. My point is you cannot ignore something you truly enjoy like pizza or whatever but you can use it as a reward for other changes that will add up to less weight and a healthier lifestyle. Another tip - for fat burn a fast walk or treadmill will pull the calories off the fastest. Sit ups can actually make your abs underneath the fat bigger and dont burn the calories an full body weight exercise can. I get asked about this at the gym allot. You cannot target where the weight comes off with a specific exercise, it doesn't work that way. Get on the treadmill to burn it off. Fast walk not a run does it.
Weight management is tough and takes commitment. Just dont let a slip turn into a permanent slide and you will be fine.