I'm a year older than you, I don't get motion sickness, but have always hated traveling, and those marathon trips leave me discombobulated for days afterwards. But I've picked up a few chestnuts here and there so I will offer them FWIW.
First, research the flight options thoroughly. There are always many ways to get there, and the best way for you isn't always the cheapest.
Second, prepare for the trip. I have a checklist that I use that includes a gear list, and things like "check passport expiration date", "call the Credit card company", "ask about malaria pills", "get a pocket dictionary", on and on and on.
Third, get in shape for the travel and the diving. Exercise, diet, swim, get a tan, get healthy.
Fourth, during travel I treat all surfaces as if they were glowing bright orange with disease organisms (because they ARE), wash my hands often, and never touch my face. Bringing your own food is preferable to eating in planes and airports and I usually take dried fruit, nuts, health bars, etc.
Fifth, get one of those inflatable neck pillows, they are great and let you sleep without breaking your neck.
Last, my wife and I like to get to the destination a few days before the diving starts. This gives us a chance to recover from the travel, see the place, settle in, and snorkle or do a checkout dive.
I can't advise you as to whether you should go, but they say that when you get old, it's the things you didn't do that you regret the most. YMMV