Any advice for staying calm on long flights?

So here's the deal. I'm not terribly affected by my emetophobia much anymore, I have my anxiety around it very much under control and I have the paranoia under control for the most part too. But I'm about to enter somewhat uncharted territory.

In a few months, I'll be flying for the first time in five years. Motion sickness has never been much of a problem for me (outside of boats) like I never feel sick in cars or on buses or anything, apart from extreme circumstances maybe and I've never actually gotten sick on any mode of transport.

In the case of planes, I don't recall ever even feeling sick on a plane. But I've also never been on a 7.5-hour flight which is what I'm venturing on in April. And I have always been a nervous flyer in the sense that I tend to worry that I could get air sickness, in spite of the fact that it never happens.

This has all been kind of fine up to this point because I've never been on a flight longer than 3 hours, but I'm concerned that my anxiety will build over the 7 hours and that I could have a full-blown panic attack. I know this probably sounds ridiculous on account of me never getting motion sickness but just the fact that this is the longest I will ever be stuck somewhere that is a potential nausea-inducing environment that I can't get up and run away from is unsettling me greatly.

The thing is, while I have the emetophobia under control mostly, I haven't been sick since 2006. And I don't know how I would react if it actually happened or if I felt like it was going to happen.

So basically, does anyone have any tricks or methods that they use to keep control over air sickness concern on long flights? And any advice on what I could eat, drink or what medication I could take to prevent it actually happening? I think if I could find a way to relax I'd be fine but often for me relaxing my mind from emetophobia related thoughts involves getting out and going for a walk. Can't do that on a plane.

Sorry for the long post. Any advice is much appreciated!

EDIT: Also, this is my first time flying without either friends or family. So no one to talk to/distract my mind with. Worrying!

EDIT 2: Awesome. Tons of great replies here. So looks like some of the key solutions are noise-cancelling headphones, a medication like Dramamine or Benedryl, and most importantly a ton of things to keep the mind occupied. Thanks everybody!