I need a Diet and Exercise Plan for busy people!

I really need help finding a diet and exercise plan that I will stick to. I am always extremely busy. I go to college full time and I work as a waitress around 30 hours a week. Between classes, homework, work, family, friends, & errands, I don't have much time for anything else. I have tried many different diet and exercise plans over the course of the past 4 or 5 years. I can never stick with them because once my work or school schedule changes, my exercise plan or diet plan conflicts with it. It's hard for me to eat healthy all the time because I have to eat out a lot when I'm not at home. I love going to the gym, but I am not a morning person and I like to relax at night. Maybe I'm just making excuses, but I just feel too tired to work out when I actually have some free time. I am exhausted from the other parts of my life. Please help me!