I'm only a student at this point, but plan to continue my pattern once I'm working. I work out every day in one form or another. I sometimes wake up at 4 am to get a run in before heading off to clinicals at 5:30. I lift 2 times a week in the late afternoon/evenings. I also walk every day and go to zumba once a week. At this point, the running is about 3-4 days a week, but I'm not training for anything big right now. When the next marathon training comes up, that should be interesting.
I precook healthy meals on Sunday and either refrigerate or freeze depending on when I plan to take them to school/clinicals. I have noticed that my biggest problem is getting time to drink water on those days, so that's my big focus now.
Basically, you can make it work if you plan ahead, it just takes extra thought.
Working nights was best for me. I would get up around 4pm, do my workout, at 5:30 shower, eat, pack food for the night and leave. I simply couldn't do that if I worked days, I'm a night owl. For a long time, if work flow allowed (I was in ICU) every hour I would do one set of pushups in an empty room or other appropriate place. That would take only a minute or so and allow me to get in a whole bunch of pushups while working. I wouldn't try the pushup routine until you are solidly entrenched somewhere, know the location, know the routine, and have a good rapport with your coworkers. You don't ever want to be perceived as neglecting patient care. There were nights when it was too busy or crowded and that is the only unit I've been able to do that. As for food, bring a big cooler of easy-to-eat-food. Hard boiled eggs, for example, are a quick and easy protein grenade. Hope that helps.