I need help please, don't know where to start!?

Ok so I'm 25 years old, 5'7 and I weigh about 145 pounds. I would like to loose 20 pounds but I just don't know how to stay motivated to exercise and diet. Overall I eat right but I thought maybe going on a restrictive diet like lowering my cabs or eating more greens and protein would help. I work about 55 hours a week and have a full-time school schedule so I really don't have a lot of flexibility to workout. I think I could however spare an hr or so a day but I don't have the discipline. Can somebody please give me ideas on how I can get motivated to loose this weight? Any diet and exercise ideas are also appreciated! Thank you!!!