By societal standards, humans are inherently lazy. From an evolutionary standpoint we don’t do anything we don’t have to. Why would you?
The problem we are faced with is that life these days isn’t particularly challenging in terms of physical exertion. We have evolved to adapt to physical hardship and scarcity and rest when we can, but we have built machines to lift things and take us places, and seldom is there anything you can’t get within 24 hours of ordering it online. The result? Catastrophic ill health throughout the developed world, caused by entirely preventable non-communicable diseases like heart disease and type 2 diabetes.
We are stressed, under slept, get outside too little, eat garbage and exercise too infrequently to protect ourselves from the aforementioned dangers we face in the modern world. For those of us not already engaged in a recreational sport, the absolute last thing we want to do after a long day at work is engage in some form of physical exertion. We typically want to turn off our brains and do as little as possible before the cycle begins again.
Types of training typically identified as ‘cardio’ are a hangover from the idea that heart attacks were caused by having a weak heart. If cardiovascular training strengthens the heart, then it will prevent heart disease. That’s why there’s no heart disease anymore.
Cardiovascular endurance is only really required for things that specifically require cardiovascular endurance, just like the ability to squat half a ton is only necessary when you have to squat half a ton. Which is never. The capacity to hike up mountains, sprint for a plane, have a fun bike ride, kick down a door, throw someone through a wall, pick up Mjölnir, rescue a kitten from a tree etc. are not to be found on a treadmill or elliptical and hence, in the absence of any other form of training, renders ‘cardio’ a total waste of your time. Never waste your time.
But Fat Burning
Cardio burns mass, not fat. Fat is included in what cardio burns, along with muscle and time. A declining scale weight does not necessarily mean good things, as losing muscle mass is one of the best ways to ensure the acceleration of your own decrepitude. Eating and sleeping well, managing stress and lifting weights is a sustainable and superior ‘fat burner’ than any time spent wasting away watching TV on a stationary bike.
DO NOT DO IT*
*unless you like it, just be under no illusions about its potential worth(lessness).