How can I make a workout harder?

I'm trying to figure out how I could have possibly made my workout at ASA harder. Let's see, I have a broken rib (okay, mostly strained, with the ligaments/cartilege between the last fixed rib and the first floating rib traumatized), migraine number seven this afternoon, that time of the month yesterday, I haven't exercised much in the last three weeks, and I ate a half sandwich just before I went over to ASA.

I wasn't actually planning on working out, but G's attitude is so infectious, so encouraging, that I just had to try. I did okay, but I'm definitely out of shape.

Yet, I'm still not sure show I could have made the workout any harder.