Make sure that you remembered to go to the bathroom beforehand.
When the formerly fat person working the desk says you may step on the scale, you do.
Make sure there is no air in your lungs because Physics told you that air weighs something when you were in 12th grade (perhaps the only thing you remember about AP Physics except shooting the laser at people across the quad).
Breathe a sigh of relief when they tell you that you lost 5 lbs.
Now comes the true irony. They say you should consider exercising some or a little more. You scream to yourself "I'M TRAINING FOR AN IRONMAN" then you demurely explain that exercise isn't your problem. They look at you confused.
Later go home and don't wimp out on your bike trainer workout since you have to do the weigh in ritual again next week.