At this point in my weight loss I have lost 50 pounds and need to lose about 30 more before I'm at a "normal" weight. It's a slow and steady process, but I'm working hard and sweating a lot. When I'm at the gym I am not the biggest girl there anymore and while that makes me happy, I can say definitively that when I see a bigger person at the gym working out, my first fucking thought is "Good for them." Seriously. We aren't children, why are we afraid that other's will treat us like children?
If somebody were to go out of their fucking way to make you feel bad about bettering yourself are you really worried about what they think anyway? You can lose weight, they will always be a dickface. Whatever is keeping you from working out, you need to wrap your brain around that and confront it. No one is laughing at you, no one is going to say anything to you, probably, no one even fucking cares that you are doing it. It's easy to project your own worries and assign them to others, it's harder to walk out your front door and get sweaty for an hour or two.
Don't sweat the small shit, sweat the long fucking walk you are about to take.
