I was actually talking to my brother in law who's a surgeon and he was telling me how basically everyone involved in sports gets it around your age. It's just a crummy part of our body breaking down from all the strain of being so active.
Many of us may actually get it far earlier if we have injuries like ACL/meniscus tears, which is why I pay extra attention to do everything I can to slow down the deterioration of my knee after 3 surgeries.
BA's tips are spot on, and especially make sure you keep your legs strong in the gym. The stronger your legs, the less strain your knee will take and the slower your knees will deteriorate. Also, if you do cardio, don't do running, it's not great for your knees and riding the stationary bike or elliptical trainer is a lot better.
And as already mentioned, canted bindings are awesome too. I basically only ride canted bindings nowadays too (which makes me sad that the NOW bindings don't have canting).
On the plus side, we may be the last generation affected by this kind of arthritis because stem cell treatment is making leaps and bounds in treating joint arthritis and regrowing cartilage.