You work 3-4 14 hour shifts, okay...what are you doing on the 3-4 days off you have a week? That's plenty of time to work out!
Try joining a gym that has a circuit or group workouts. I personally like Curves, especially since the Curves I joined offers Zumba throughout the week. Curves is a 30 minute full body workout that is as easy or as hard as you make it.
If you have a hard time working out on your own, doing structured activities are better. Unless you know what exercises to do, it's less stressful to just join a group and have at. That way, you know how long it will take and the bits of what moves to do are all figured out for you - you just have to show up.
* I'm often reading and posting from mobile and Siri loves to make a mockery of the English language.