Core Strength

via BicycleMagazine.com

Get your core going.  It's been on my mind a bit I've got to work to keep mine strong.
Having a strong core is everything.  It is the foundation for the muscle movements and how they all work together.  If you have a squishy middle, you are more likely to have a sore back, on or off the bike.  You can have the strongest legs in the world, but you need a solid middle to help them do there job.  My favorite exercise called the bicycle crunch.  Do a few minutes of these to feel the burn.  Two photos below taken from here.  A great site for ab muscle building.

or sit-ups or whatever, I just like this photo