Sorry to hear about the heat. It was 70 and sunny today in Oakland. The weather is awful out here. AWFUL. However, the earthquake that is destined to lay this place to waste is lurking somewhere in the Hayward or San Andreas faults. Strain is accumulating over time and no one knows when it will give way. I digress...
Your knees are going too far forward. This, in general, puts you slightly off balance on your toes. Don't let your knees go so far forward. Sit back with your butt more. Drive your knees out harder. All that should help a bit.