Nice thread you started here. Congrats on starting a treadmill program for yourself. Your goal seems to be to lose weight but I suggest you also consider the very real benefit to your cardiovascular system. Your workouts and a good diet will help your cholesterol profile and can help to prevent plaque buildup in the arteries.
I started having shortness of breath at 53 years old and found out I had clogged arteries mostly due to lack of exercise and poor diet. I was not overweight.
I have had angioplasty and have a stent in one artery.
Anyway to make a long story short I'm now 65 and I do the treadmill 5 days a week for 30 minutes at 3.6 mph and a 14% incline. I also walk 2 to 3 miles outdoors every day with my wife.