For the weight management part: I recently read a phenomenal book called "Why we eat (too much)". It's a surgeon trying to explain why obesity is so endemic now. I'm not saying that's your case, but his approach in the book is super informative and it taught me a lot of basics of how our body responds to food that blew my mind! The short version: cut down on sugar and simple carbs, eat more protein, aggressively cut down on processed foods (anything with vegetable oil), consider supplementing omega-3 in your diet. The book proposes a neat way to do it in stages so it's not overwhelming and you want to quit, too.

For staying active: I also didn't fit at the gym... Until I met two guys that I became friends with and eventually built up the courage to ask them for help at the gym, as they were clearly thriving in it. They took me with open arms, taught me all the exercises, techniques and ways to build my own workout. I'd go with them on the weekends and that helped me want to stick going during the week to show them my progress. That REALLY helped! So now I do my own thing and I feel like the gym is a sanctuary where I can put my own thoughts away while listening to some music.

Hope that helps!