How long do you have to exercise to lose fat?

Answer 1

It depends on how much you weigh and how hard you exercise.

Here's a very, very rough estimate.

If you're an average person, to loose a pound, you need to exercise
for 12 hours at a moderate pace, or
6 hours at a vigorous pace.

So, if you add a half hour of moderate exercise to your day, every day, it will take you almost a month to loose a pound. That's 12 pounds a year.