Firstly, well done for doing this sort of job for so long. I don't think I would be able to. But also I recommend finding an another job or saving up so you have a cushion to find a job before you actually quit your current one. I actually did quit my job partly due to my stutter and have been pursuing one of my hobbies as a job for the past 2 years. But for that I saved up enough to do so and I felt I was ready to pursue this. Also definitely try to go to the gym. It will help your self confidence and maybe you'll find it relaxing once you're there and maybe you'll find a passion for it. Try going a couple of times a week at the start then increasing it if you feel like it. Good luck man.