Until you change your attitude, I suggest you don't bother enlisting into any branch of the military. You will fail, and you if by some chance you don't .. you will force others to carry your load.
Ft. Benning is home of the infantry. Light PT is not an option.
No matter what MOS you choose, you will be required to put forth some slight physical effort. Unless you get up, and get yourself into shape, you will fail.
Change the attitude, then worry about PT and enlisting.