Anerobic Cellular Fermentation

We can definitely function on anaerobic cellular respiration but I don't know if we can rely on it. This process if called Lactic Acid Fermentation- which is when we break down glucose in our cells. This happen while we are exercising our muscle cells obtain very little energy, it produces two ATP molecules instead of 36. So, I wouldn't say we can rely on it. We can keep exercising to produce more ATP's but this can only go on for so long... which is why it's proven that we can survive without food for at least two weeks.
Warm blooded animals are much more active than cold blooded mammals because they can generate their own body heat in cold temperature environment. Warm blooded animals convert their food into energy. Their body requires certain temperature to convert that food in to energy. Cold blooded animal's muscles depend on chemical reactions, which is faster in hot environment and slow in cold, so they tend to be very slow when it's cooler.