I thought it was just a stressful job. I had no free time, my boss was verbally abusive, but I thought once I quit it would all go away. After I quit, I thought maybe I was depressed: I was unemployed, my brother had recently suffered a serious injury. But, when my life started getting better, my mental state continued getting worse.
After almost a year of living through severe apathy, lack of focus, and even some short term memory loss, I finally decided it was worth mentioning to my doctor. After running some blood tests, she diagnosed me with a severe B-12 deficiency.
I couldn't believe that after all of those months of wondering what was wrong with me, and why I could never complete a task, all I needed was an injection and some B-12 supplements. I now take sublingual B-12 tablets everyday, since I have a severe aversion to shots.
I feel so much better. I am finally able to keep up with an exercise program for more than two days, I can remember events from the past week, I have a much more vibrant and positive outlook on life. I actually notice things! A car ran a red light, and I saw it just in time and was able to react. When my B-12 was too low, I probably wouldn't have seen the car, because it was so hard for me to physically focus while driving.
For anyone who says they feel tired, lethargic, can't focus or remember, I've been telling them all to go to a doctor. It could be a thyroid or B-12 problem. Don't assume that just because you don't know what's wrong with you that the doctor can't figure it out.