While you should think of your program as being as much a part of your recovery as visits to the doctor, try to enjoy yourself. Exercising can be a lot of fun. And it can be very stimulating.
If you have days when depression and boredom get you down and exercising seems like too much of a burden, just remind yourself of all the benefits of exercising regularly. Your program will improve your energy level and stamina, improve your appetite, help you relax and help you sleep at night.