Theory

The trainer is a self-chosen torture device that people willingly subject themselves.  You know you do it.  Don't lie.  It is a horrible way to spend your time, especially time on a bike.  Of course you get a benefit from hurting yourself, the benefit is that you now have a larger threshold for more pain.  Boy, isn't that a barrel of monkeys?  We do something that hurts, so that we can endure more pain, so we take on more pain just to be able to hurt more?  Are you following this?  I'm writing it, and I'm a little lost.  This makes no sense at all.

I'm hurting myself so I can hurt myself more, but you know at a higher level. 

You know the point in time when you are going cross-eyed?  When the legs are about to stage a revolt, your lungs are looking for a change of address form, and the brain has checked out long ago?  Time stands still?  The fabric of time unravels and you are stuck in a warped limbo state that has no end or beginning.  This is akin to when time slows down during a crash.  You stress the body to the point where your brain feels that it is in danger and your senses become heightened.  Therefore, you are able to slow down time, perceived time that is.

This phenomenon is awesome, so awesome because now you can experience the excruciating pain in John Madden like slow motion with commentary and HD video instant replay.  How lucky is that?  Now a 3x10min Threshold interval session feels like a lifetime with your hand caught in a door.  Perceived time is a cruel and malevolent bully that will get your lunch money every time you dip a toe into the Red-zone.