Best thing to do is start slow. I mean if walking a mile nearly kills you then try just walking for 5-10 mins at a slow pace and work from there. Stop the lazy things too. Park further out in the lot so you have to walk further. If you take an elevator/escalator any time, take the stairs instead. On lunch break don't just shoot the shit with the boys after you eat, go and take a small walk. Everybody that sees this will tell you diet is everything...and they are right! If you don't change your diet and do everything I said it still won't amount to shit because if you are putting in more then you are putting out then you are just spinning your wheels. You are in the right place though my friend. There are some vastly knowlegdable bros on this form. Check out the diet and nutrition section too. That will give you some ideas. Good luck brother!