You can do it. Two and a half years ago I was in the same place as you; 285lbs, no physical fitness to speak of, not watching diet at all. Finally had a 'moment of clarity' and decided to lose the weight. Averaged about 1 to 1 1/2 pounds a week over two years. There were times the weight wouldn't come off at all. Then there were weeks it would melt away. Just remember to stick with it and you WILL be rewarded in the long term.