After making the commitment to drop body fat through exercise, you need to set realistic expectations for yourself, especially if you have never exercised previously.  I created this bell curve to demonstrate the way you should be thinking about planning your exercise program.

Exercise Bell Curve

When you first start out, your frequency should be lower (2-3 times per week) as well as your intensity (moderate effort for 20-30 minutes).  As you start to make progress (i.e. as your body fat decreases), you should plan to increase both the frequency and intensity. As you get near your target, you do not have to work as hard in your exercise routines to maintain as long as you are continuing to stick to your nutrition plan.

At one point during my downward journey, I was really in a hurry to continue my progress, and would have as many as 8 exercise sessions per week, which included split sessions between morning and evening.  However, my resistance training rarely went above 40 minutes, while my interval cardio training was never more than 20 minutes.  So even though I was at the gym as much as 8 times in a week, the total time spent was a little over 4 hours.  Now that I'm at the far right of the curve, my total time in the gym is more in
the range of 3 hours - extremely efficient.

I've seen folks time and again try to start their programs in the middle of the curve and burn themselves out in 2 weeks or less.  Start slow, then kick into high gear, then look to taper off to maintain.