"Strength doesn't arise from physical power, but from unshakeable willpower."
Mahatma Gandhi (1869-1948), indian lawyer, leader of indian liberation movement

Undoubtedly wise words from a wise man. On the other hand this doesn´t mean that musclepower is something only idiots consider as worth to gain for.

In fact, everybody who ever had a try in hard blue-collar working or was seriously engaged with sports knows that you need lots of self discipline to do this regularly for a longer period. Otherwise you could as well just let it be.

Assumed you agree to that point, figure that self discipline is nothing else but willpower. It's not mind over matter.

It's mind and matter!

It's resistance.

Overcoming.

Concentration resulting in rivers of sweat. Pain that clears your mind when you finally realise you have made it. You have merged with exhaustion. You taste the goodness of having nothing more to give than you have given right now.

Physical strength often is tightly linked to a strong will. It can also be a statement of deep respect to nature, which is always challenging strength of any means to meet its sometimes raw and wild aspects. It can even be a statement for the love of life. This is the only explanation for the survival of men like Andreas Niedrig, who mutated from a heavy junkie with a ten-year career in this obsession to one of Europe's best triathletes. Need i to tell the story of Lance Armstrong? The winner of 1999 Tour de France had been given a 50/50 chance of surviving when the doctors told him he had testicular cancer in 1996. Dig that, it's almost unbelievable!

To draw a conclusion, i suppose that physical strength is something that shouldn't be underestimated. It is well worth considering to move your ass and suffer some aching muscles or getting a stitch. Maybe it won't necessarily save your life, but it will definitely shake it up a bit.