after each of my knee surgeries i gained a ton of weight and getting back into the gym was intimidating for me too. the best thing i can tell you is that once i put my nose to the grindstone and started up again i got over my anxiety when i saw how much better i looked and felt. its hard at first(especially when you know the guys there and they harass you constantly for getting fatter), but once you get in there and are able to get past that anxiety(and soreness) you will notice the changes in you, and so will others and them just mentioning to you that you look better really helps and keeps you motivated. getting past the initial fear is all on you, but remember that youre doing this for you, not anyone else, and that will hopefully keep you going strong. just remember you arent the only one out there that wants to go to lose weight, a good example of someone famous is kevin james. im sure others at that gym went for the same reason, and its a good idea to let your instructor know straight away that thats what youre trying to do. he is there to help you, so let him know your agenda and he will be able to do more for you than if you dont say anything. keep your head up, stick with it, and work hard, you will be very happy with the results. good luck man!