Don't stop training when you're tired... stop when you're DONE. All the pain is worth it for the gain in fitness. Exactly. Unusual use for a hamstring curl machine... Our customary shout out to the next generation:      

You get what you work for... not what you wish for. And working (out) for it - er - works! You should join the dedicated guys. You'll not regret it. Finish off this post with our customary nod to the rising generation of fitness enthusiasts: