No Pain, No Gain?

I'm working out in my "Spinning" class, you know the class where you ride a stationary bike like H. to nowhere, and the instructor's driving us with a fast paced clap to keep up our "cadence."
"Come on, you can do it, push hard for 1 more minute," and other such motivational phrases are being shouted out over the beat of the music. I look up on occasion, to see if the mirror reflects proper posture, to see the gaudy purple walls, to see something besides the pedals below me spinning. I finally figure out why they call it a spinning class. Duh. I'm panting like a dog, and checking out the clock to see how many minutes before I can say I did it and stop.
And then she says something that captures me. It goes something like this:
"If when you get tired, you slow down, you get more tired.
If you push through it, you get stronger."
How many areas of life is that applicable to?
I've always had issues with the "no pain, no gain" slogan. I question it's truth, and the implication that all pain is so helpful. In my mind,there's bad pain and there's good pain, productive and non-productive. And the way we handle it also determines the gain in it. Pain can make us bitter or better , to quote professor I had once.
But there is an embracing of the pain in a healthy way, and a strength that comes in the pressures of life's trials when they are embraced and taken to the cross of Christ.
This feels unfinished, but right now I'm done.