A lot of people say that they hate to exercise. Probably because of the uncomfortable feeling of being out of breath while your heart is pumping furiously. For me, when I get to that point, I acknowledge that it’s hard, but I also realize that this is where I need to be for my internal furnace to burn fat. Are you getting to that point during your workouts? Where is the actual point when our body says "enough" and starts burning fat?
Our muscles are primed to burn fat, and it is our most concentrated form of energy. When we begin to exercise, we burn glucose and glycogen, but it only takes a matter of minutes to shift to fat. It is not an abrupt switch, more like a smooth transition that works better as the body becomes more fit.
At first, glucose and glycogen are the main energy sources. The brain immediately sends a signal to the fat storage areas to send fuel then to the lungs to start breathing faster and deeper to supply more oxygen and start removing carbon dioxide, the exhaust gas from muscular work.
The actual speed and ease of the shift from anaerobic to aerobic reflects the level of fitness. Warming up or starting slowly also helps the process, because it gets the signal sent earlier and helps shunt blood flow to the working muscles.
Even after we have made the shift to fat burning, we continue to burn some glucose. This causes lactic acid to be produced in the muscles, which then goes to the liver where it can be recycled back into glucose.
The human body really is an amazing machine. So, get uncomfortable and get your internal furnace fired up. Make your workouts count!