after you lose a good amount of weight (maybe 15-40 pounds) get involved with sports or something a guy 6"6 would be good at football. to help ur body stay fit.
if u get hungry start eating healthy foods with more protein because they will help fill you up more.
after about 2 months or so of walking start to run/jog about a block of you walk. try to walk about a half a mile a day at the very very very least.