How Hard Do You Work Out?

How do you define how hard you have work out each time you go to gym? I mean if you're doing cardio or resistance or even RPM classes. How do you define if you're really working hard enough? Is it the non stop beating of your heart after each track? Or the amount you sweat after the whole class? I saw one of the RPM instructor who sweat so much that it created a puddle of water underneath his bike. Well, I think we all agree that the more we sweat, the more calories we burn in our body. I have this bad habit of weighing myself every morning before I go to work and each time I reach home after gym.

My weight can really varies very much during the weekends. I think I ate a lot during the weekends hence I work like mad during the weekdays. For instance today, my lunch was so crazy. I had deep fried calamari, fried chicken and lamb curry with vegetables. I was so damn full after the fulfilling lunch I had. So I would need to work out extra hard tonight. But I skipped Cindy's Body Pump as my legs was still a bit sore after the challenge last night. So I just did RPM and Combat class to sum up my exercise tonight. Hopefully I burn enough calories tonight to compensate with the super lunch I had today. So how bout you all? How do you weight your workout?