I have worked ALL shifts throughout my life at some time or not. While it is usually difficult when first making the change, one should be able to quickly get their life in order and in sync to perform ALL duties one would when not working odd shifts. I used to work 60 hr weeks when sometimes I worked throughout the night and then onto the next day. For 12 years I did night school while on this schedule. I still had time to make it to the gym. Maybe not on the day or time I planned, but I still had extra time somewhere in my life.
It really wasn't until I got married and we had children that my priorities shifted and everyone elses scheduled out ruled mine. Then I had difficulty in getting and staying in shape. But in 20/20 hind sight, I know I could have done it had I really wanted to. Maybe in smaller increments, but I could have still done something. Also, nutrition should NEVER have been an issue. I should have put my foot down here and/or made healthy dishes myself instead of just accepting the many foods I knew were not all that good for me.
We can always come up with excuses, when we should come up with solutions.