I only do walking, and sometimes swim, play basketball or bike leisurely. Basketball is my only real strenuous exercise. I tend to exercise longer, but not as hard. Some of my friends find it good to work out very hard for 15-30 minutes a day, and mix up what they do. I don't see any reason to exercise very hard, for long periods of time. That just makes people hungry, and they eat more, which means that they are just exercising, but eating the calories back, so net, not that much of a negative calorie balance.
I started out not really able to work out very much, because of my heart issues, so the decision was out of my hands. So I focused on diet. I started walking to my mailbox, which exhausted me, and as I dropped weight, I exercised more. Now I do 45-75 minutes a day. I don't go torture myself in the gym, instead choosing to "play " away my calories.
I put in 1750 calories ( 250 a day) burnt for the week, and got a range from SP. As my weight has dropped, I just cut down little by little on the calories. I don't eat extra if I play basketball, instead of walk today. I just eat the same, and know I burned an extra 200 calories.
If you are losing 1-2 lbs a week, and eating 20000 calories for example, there is no reason to eat 2300 if you burned 1300. Just stick with your average calories eaten. We all have times when we feel awesome, and burn more, but then follow it up with a week we don't feel like waking up to go exercise. It averages out. Look at the average calories in the weeks you lost weight like you wanted, and stick close to that.
At a certain point, you don't need to burn any extra calories. I walk 45 minutes most days. I could easily walk 60, but it takes me about 45 minutes to walk the 1.5 mile path along the river. I could do it twice, and get 90 minutes, but why? If you have been exercising for a while, you should just pick an activity that burns a certain amount of calories, and that you enjoy doing, and do it 4-7 times a week. That way your calories burned doesn't change, and what you have to eat stays around the same.
I wake up, walk 45 minutes, and eat about 1800 calories a day. No math problems to factor out. This is your life, not some chore to figure out. Make it simple. Eat in range, and exercise a certain amount, and as long as you lose 1-2 lbs. , just relax, and enjoy the success.
In the end, a healthy weight will lead to exercise. If you feel like you are pushing yourself too hard, you probably are. So by focusing on weight loss, you will increase, and be focusing on, exercise. They aren't exclusive. Diet will help with weight loss, and exercise will make you healthier cardiovascular-ly. I think you are wondering about exercise as a weight loss tool, and it isn't a real good one. Burn whatever you need to get the cardiovascular benefits, but not extra.