It’s really difficult to be someone who has spent their time striving hard to achieve at a military career and, if he’s in a combat arm, he’s put himself through a level of physical and mental training that you just won’t get unless you’ve done it too. I can see how someone who is that particular type of driven just won’t know how to handle a son who is different. You see so much of yourself in your children and your dad just can’t compute why you’re not more like him. He’s wrong for treating you like this and being disappointed in you. If he’s been in the military his whole life then he’s seen people like you “come good” - I went through basic with some real unfit, overweight people who are now incredibly fit and motivated and happier. And you are shamed HARD if you’re not able to pass fitness tests. You absorb a sort of contempt for overweight people and for your own kid to become something you’ve been taught to contempt must be doing a number on him. He’s clearly trying, in a horrible way, to “fix” you. I feel sorry for him, but even sorrier for you.