I don’t like it when “fat” people are stared at negatively when they are running or exercising at the gym.
Hell, they are changing their life! They are on a journey.
You should mentally congratulate them. They should be applauded just as much as that person running a mile in 7 minutes without breaking in a sweat. In fact they are working harder than most. 
It’s a journey. Whatever level you are at, do NOT give up. You will get there. Be brave. It will take time. Be proud. You’re amazing.