I'm no fitness expert, but I reached a point in my life where I needed change into a healthier lifestyle due to age/medical condition/ and weight. I peaked at around 210 lbs, high blood pressure, high cholesterol, and mi or depression. My biggest addiction was to soda, particularly Coca~Cola. My diet sucked because I was at a job where I worked 12 hour shifts and ate tons of take out. First thing I did was cut down on soda, went from 4 cans a day to 1. Then cut it out completely, replacing it with water or juice. When I realized how much sugar was in juice I cut that out too. I drink at least 100 ounces of water a day. The only other drink I have is milk with cereal or almond milk with a protein shake. I began bringing my own lunch to work. Spinach/Romain Salad, 2 hard boiled eggs a piece of cheese and some unsalted nuts. I lost about 15 lbs in 2 months and was stuck. I spoke to someone at work who lost a bunch of weight and he said when he reached the point where diet wasn't cutting it he started doing an exercise program p90x. I began to do some research and realized p90x may be too advanced for me, but there is a newer program geared for beginners called p90. I began that 65 days ago and I've lost 10 more pounds, more importantly I've tone my body and gained muscle. The program is 90 days that progresses through a new set of exercises that become more complex. Alternating days between cardio and body sculpting. They also show modified exercises if you're having difficulties. I highly recommend the p90 program. At 270 lbs. I wouldn't go running, it might put too much strain on joints, try a bicycle or if possible swimming. You've got this, don't look at it as going on a diet, look at it as a lifestyle change.