Its hard to keep going

I went to the gym today. It was a biotch to get up this morning. But I did it. My weight yo-yo's like a bear. I hit a new low every Friday, and then by Monday, I seem to gain it all back and then some. Then I spend the rest of the week working hard at the gym, trying to watch what I eat, and thinking "well, this will be the week I slide, and don't lose anything." Yet, somehow, I hit a new low, albeit only 1-2 lbs less than the previous week, and we move on. Just once, I'd like to have a weekend where I go to the gym on Monday and I am no heavier than I was on Friday when I left. That would be nice. Trouble is that weekends are my cheat time with eating. The bigger trouble is that I use the whole weekend to cheat. I really need to stop that.
I was contemplating doing a cleanse this week, just cuz I felt so yucky from the weekend. We'll see. I get bummed because I know I should be doing more weights at the gym, but they are hard. And I know that I should be doing Jillian's workout, but it is HARD. I don't like doing jumping jacks, and skipping rope at the gym - I feel silly doing it there in front of everybody. So, for now, I just keep going.