Try strengthing your lower back and develop a routine for stretching not only your lower back but your body everyday, not just before a round of golf.
As far as the exercises for strengthing your back are concerned, a good list can be found at:
http://www.bodybuilding.com/exercises/finder/lookup/filter/muscle/id/5/muscle/lower-back
I actually prefer to play by myself. Mainly because it helps me focus on myself and what I need to improve on. Plus you never know when you might get paired with another solo of the opposite sex. lol