Greg, personally I think as we get older the opportunities to undertake our photographic activities become less, due to other commitments and physical problems etc. By sharing out expedience and expertise we stimulate and keep that knowledge to the fore in out memory, I find that if I have not done something for a while I have a bit of a memory block on how it was done, by teaching others it keeps it fresh in my mind
Fortunately Craig, I still have all my faculties opperating as they should so at my age, I'm grateful and hopeful that continues for some time yet. I'm always shooting something on a daily basis and experimenting with Photoshop, so the mind is always busy. I do one-on-one help and tutorials and that keeps the brain ticking over as well.