Are you going to be doing any cardio in that time (or you may already do).  You probably already know this, but I believe burning ~250 calories more than you intake a day = 1 good pound of weight (that is, not water weight) lost a week.

My husband is the same size 5'11 and in the 180 lb range.  He would love to be 165 again, which is about the weight he was when we were first married.  But he was also running 100 miles a week back then. 

The best he can do now is to stay under the 180 mark (loves those pringles too much)  without going thru drastic measures.  He finds running makes a big difference in how his clothes fit and just overall fitness even if he can't be 165 again.  He looks really trim and fit in the 170's range and since muscle weighs more than fat I'm sure that's a big part of why he looks so good.  When he increases his mileage the pounds just drop off him even though his eating doesn't change. 

Actually, I believe it's 500 calories a day will lose you a pound of fat a week, since I think there are 3500 calories in a pound of fat.  Though you have to make sure, if you're not supplementing it with exercise, that you eat even less than that, if 1 lb a week is your goal, since your body tends to lower its metabolism by a little bit if you reduce your calorie intake.  

I've been trying to walk at least 2 miles a day on top of my regular activity.  That's about 500 calories there I believe.  Plus I've cut down on the junk.

I am not sure I'm going to make the 3 pounds I hoped to lose in the first week though. So far, I've lost about a pound and a half.

Usually a mile is worth about 100 calories and that depends on how fast you're going.  The faster, the more calories burned.  So two miles is somewhere along 200 calories.  The variables, of course, have to do with how much you weigh and the speed of your walking.  Running one mile would burn slightly more than walking one mile. 

If you have  treadmill access that you can program with your weight before you start it  will tell you how many calories you burned as it gives your distance  So this will give you an idea when you go outside.   Try walking  one mile on a treadmill and then running one mile and see what the diff is. 

Well one week has passed and I only lost 1 lb.  I'll just have to work harder.

or run..........

A light strength training program will also help.  Musicle burns more body fat.  maybe try taking hand weights with you on your walk or do 3 reps of 20 curls.  There are tons of programs to follow online.

It's funny, you're at about the same weight and height as I am (I'm a tad shorter, and a pound or two heavier), and are doing more or less the same thing I am to drop the weight (eating better and walking a lot).

One thing that's worked for me in the past is a little bit of more strenuous exercise once a day:

• 15 push-ups
• 15 situps
• 15 squats (with two 15lbs weights)
• 15 dumbell curls (again, 15lbs weights, each arm)

Running through that list twice at least.  Toss in some lunges if you want more on your legs (with weights).  When I can actually dedicate myself to the above, plus walking and eating better, the pounds drop off pretty fast.

I have to drop the 30lbs I gained since I started working here 

Okay, I've started using the elipitical machine a bit and walking more.  I also plan to start doing some weights, push-ups and situps.

I'm hoping to get to 173 by this Sunday.

If you REALLY wanna melt the pounds off do some kind of cardio intervals. Like a minute or two of very intense fast walking on 7 to 10 degrees of incline followed by a minute or less of dropping back down to zero and slowing down for a brief recovery and then ramping up over again. Same thing for pushups: do ten and then rest for one minute and then do ten more. I do ten sets of ten like this about twice a week or so and it really builds upper body strength.

Anyway intervals! It worked for me.

with your plan it sounds like you're going to first gain muscle.   Muscle weighs more than fat so don't be surprised if you either don't lose at first or actually gain a bit.  After that the muscle will burn off the fat and that's when you see actual weight loss. 

Roy's right.  Intervals are really beneficial to your workout plan.  When I'm activly doing intervals the weight flies off and the clothes start fitting very loosly.  Not only that but your endurance is so much better after just a couple of weeks of doing intervals.   You can also do a pyramid which is to work your way up to a particular speed and back down the same way for  whatever time limit you set.. 

New week...

The new week has arrived and I've lost enother pound.  I'm able to fit comfortably into my dress clothes again which is part of the reason to do this.

I still have 6 pounds to go to reach my final goal but I feel pretty good reaching the half-way mark.