Even if you're not a million-dollar professional athlete, physical strength is still important in your life. The machines made by man can't replace the machine that is man. Arthur Jones, inventor of Nautilus equipment, told us so a couple of decades ago. And it's true. Muscles get Andre Agassi from baseline to the net, and they either pack more power into his strokes or provide a greater number of powerful strokes before tiring.
Muscles are where energy is released, power is produced, and where movement originates.
Because the condition of our engine has a lot to do with the way we look, feel, and function, strong muscles are very advantageous. That how much will waste away or atrophy. This lowers your metabolic rate. If there is no corresponding reduction in caloric intake, the result is a gradual gain of body fat. Excess fat is unhealthy - and, to most people, unappealing.