Then increase your intensity for the last 15 minutes of the hour's exercise. You can calculate your maximum heart rate by subtracting your age from 220 . Don't worry about exact calculations, these are rough estimates. If you can't converse, decrease your intensity a bit. You can break it up into two 30-minute sessions, but you cannot eat any food in between sessions.
Drinking water is okay, but no juices.
You could get up and take the dog for a 30 minute walk, then sit down and read the paper or do some chores and then hop on the treadmill for another 30 minutes, but you cannot eat any calories in between those 30 minute segments. Only drink water. Once you have achieved your desired weight loss, you do not need to exercise 60 minutes to maintain. Then you can cut back to 30 or 45 minutes 3 to 4 times a week. Lift weights at least 3 times a week.