8 Answers

This is a mantra from the cult of physical fitness. It means the benefits of exercise don't begin until you pass a certain threshold of fatigue and continue to work out.
You must work hard to achieve your goals.

You must work hard, harder to achieve.......

Nabam ... And all this is a very worthwhile thread. It’s 3:30 AM. I must work hard to brush my teeth and steam my face so I will look alive in the AM. I would rather just recline here and tap tap tap.... night all.

This is a "said" (saying) that was once promoted by fitness experts.  They would tell us that if it did not hurt, it was of no benefit.  The current group of "so-called experts", now say that you should NOT hurt yourself while working out, but push yourself only until you "feel" it, NOT to the point of pain. Some have done serious damage by following the original advice.

Its all of the above and also a favorite phrase used by political leaders when they intend to screw more money out of you( the tax payer) , to finance they lives of luxury.

It seem life is full of pain, those who suffer the most likely learn the best in this life.

Anything worth having or achieving is worth the time, effort, and sweat it takes to obtain.

This phrase can also be used sarcastically.  eg:  A friend asks for your help on a project and you end up doing the hard stuff and ask why that is and the friend says 'No pain, No gain" (a sarcastic and smart ass response).