First, you should keep in mind that our perception is a trickster, and what you see isn't always real. There's actually a mental illness relating to this where people see their flaws as extremely exagerated. Those flaws might not even be real.
But even if you truly are ugly, you just gotta accept that it's not your fault to have been born with an odd face or body, and that it's not wrong to be ugly so why should you feel ashamed or ill for something you don't have that much control over? It's also not harming anyone, so what's the point of feeling bad about it?
Sure, go to the gym, it's never a bad idea, it improves your mood and it's healthy. But when you look in the mirror and find yourself not liking what you see you should think that you're more than your appearance, and that not being beautiful doesn't devalue you.
As for pictures, I've managed to look almost cute when in reality I have a really weird face, so you can do anything if you're patient. Keep the camera far away from you for the best results, shooting from up close will deform your face.
The camera lense also plays into this. Look at this and keep it in mind every time you get a bad shoot.
