One coping mechanism I recently came up with is that I realized it's not so much the fear of crashing that I have (I've been able to rationalize about how turbulence != crash), but it's more that when the turbulence starts, I hate the unpredictability of it - I have no idea if the next bump is a small one, a big one, or one so big it will cause panic in the cabin. Thus even the smooth waits in between become angst-filled.
On a recent vacation, on the ground, I ended up playing with my kids on a "parkour" playground, running up and down hills, jumping on trampolines, getting the same feeling in my stomach and inner ear as a bumpy plane ride. So once I was back on the plane and we hit some turbulence, in my mind, I visualized myself running around that playground again. I know this sounds silly, but it worked wonders. When the bumps came, my mind was already prepared as it was pretending running and jumping on a trampoline. This helped me cope a lot, by taking me to a different place.
Many people mentioned hearing pilots attitudes towards turbulence helps and I can totally see that. However, one thing that I wish they wouldn't do is announce before the flight that a) it's going to be a smooth ride or b) there will be some bumps along the way. For me, at least, in scenario (a), if we hit some unexpected turbulence that makes it worse for me because I know the pilots weren't expecting it and (b) if they say there will be a bumpy ride, I'm bracing myself the whole time and I've been on flights like that where they ended up being 100% smooth :/