You compare yourself to others who put in the work, no matter how difficult, to get themselves in shape, and you feel disappointed in yourself. But have you ever stopped to consider that most of these people do not have the obstacles that you have, like your health condition? If the playing ground were levelled for you, like them, you might perform as good or better. It's like trying to light two pieces of wood and one lights immediately because it's dry, but the other doesn't because it's wet, and the wetness becomes a disadvantage, though both are equally capable of being set alight.
But I love what you're doing, trying to overcome your disadvantages and still have a go at it like others do. An important lesson: Don't be quick to to place yourself above others or think they are better. They may be capable of achieving more than you, but you're more successful simply because the odds are in your favour and against them, or the other way round. Think of things like: Background, circle of friends, upbringing, health challenges, etc.
But that the odds are against us is no excuse for mediocrity, nonetheless we shouldn't be too hard on ourselves when we've put in our best and the results are not to our satisfaction.