Getting your period when you are trying to get pregnant feels like stepping on the scale only to find out that you have gained 25 lbs. overnight.
Actually this is where I think that making babies is actually harder than losing weight. I mean, imagine if you could only lose weight for 3-5 days of the month THEN you had to wait 2 weeks to weigh in and find out if you lost, except you didn't lose weight even though you got all your exercise and watched your calories. Now you have to wait ANOTHER 2 weeks before you are able to try to lose weight again.