>>1225956Just with regards to exercise, heavier dudes need to go a little easier- stick to low impact stuff like cycling and swimming until you cut the weight down, otherwise you'll blow out your knees and lower back.
Once you're down to about 250, feeling a bit better (and lighter) start up on the walking, walk until you're fucked and then push it that little bit more, over time you'll strengthen up your leg, butt and back muscles, joints will be a bit limber and you won't be so wheezy.
You can do it, good luck