Hey Spencer,
Can't really tell you why I've stuck it out this long (in my 22nd year now) - still volunteer, also paid p/t fill-in guy, and paid/volunteer instructor, but for whatever reasons even after all the negative things like jacobsond and Eng34FF mentioned - I'm still here.
What I can offer is that if you're really looking to fix "retention" issues you need to focus more on what causes your members to leave vs what makes people stay.
As indicated by the numbers of "I don't know why, but I do" type answers here - it's easy to keep people with very little effort or incentive; however it is also just as easy to run them off with small & easily managed issues.
If you have contact information, go back & "interview" any members you've lost over the last 5 years and ask them why they left. Even better (if you have the funds & time) send them a Self Addressed Stamped Envelope and a note asking them to reply anonymously as to why they left.
Hope that helps & good luck. Also an "Atta Boy" for you for at least making the effort to think about retention.

