There does appear to be something to the decades old theory about exercise induced euphoria, but researchers aren't certain whether it's endorphins (recent research indicates it doesn't cross the barrier between blood and brain), dopamine, serotonin, norepinephrine or something else.

Whatever the science, I do feel better during and for hours after a ride. The worst part of the ride is usually about 10-15 minutes in, when my body suddenly realizes I've tricked it again and this ride isn't going to be over soon. But after 5-15 minutes of cramping, whining and punishing me for tricking it again (hey, is it my fault if my body is so gullible?), the body decides to enjoy the ride.

My back has gradually gotten a bit better since I resumed cycling last summer, but my neck will never get better (splintered C2). I just hope it stays tolerable. It limits my riding positions but for now the bike is set up well enough to enjoy 20-40 mile rides a couplafew times a week.

There isn't much I can do to strengthen the neck. There's bone on bone grinding, so too much exercise is potentially dangerous. I just do a bit of stretching and massage. If I stretch the neck too much, or even look up at the sky, I'll experience sudden dizziness and pain. That won't change, so I just avoid doing stuff that aggravates it.