I have several friends that are having the same problem including me. It has been a long bad winter and I know that can have something to do with it. Spring is just around the corner and hopefully getting more light will help. I'm starting to feel a little more motivated with the days getting longer, but the rain just doesn't want to go away. Yesterday I actually got up and got some things accomplished around the house. I hope it stays that way. This time of the year can be bad for depression. I hope your feeling better real soon.
See your Doc! Your options will be made clear & you don't have to have any treatment that you don't want. Depression can be treated by a variety of methods,you may not even need it. The Doc. will check you out for other possible causes of chronic tiredness. Good luck.
If you're not actually feeling depressed, then chances are it could have a purely physical cause. B12 and iron deficiencies would be the two most common causes for lack of motivation and energy, but there are others. All you'd have to do to confirm that would be to go to the doctor and have a blood test.