Fitting nutrition and fitness into work life

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First off I would like to start by saying that prior to the last 5 weeks I have been able to fit my gym & running into my lifestyle with out any issues. I have started a new job where my shifts range from 9-12 hours a day 5-7 days per week with 30-45 minutes break.I am a waiter and averaging 20,000 steps per day. Due to this my diet is little and I'm too tired to do planned activity. Any suggestions on how to become motivated and plan my nutrition/ meals and any hints and tips of others who live a lifestyle similar to this would be greatly appreciated.