I have used Provigil off and on for several years. I was given it to see if it would help me with physical fatigue, that is, fatigue that is felt in my body. It has never helped me with that kind of fatigue.
Through trial and error, I have learned to use it for mental fatigue, or mental cloudiness, or cog-fog (I think that's the common lingo). Also, it helps me with mental stamina. On days that I know this might be a problem, or on days when the mental fog is dense, I take 50 mgs Provigil twice a day (am and early afternoon), and it really helps. More than this amount makes me feel too "amped", and makes it difficult for me to get to sleep at night.
In my case, the only things I have found that help with physical fatigue are: (1) low dose naltrexone - I've been on it for a month now, so far it has helped tremendously with this kind of fatigue, (2) acetyl-l-carnitine, I take 1000mg, up to 3 times per day, about 1hr before eating, and finally (3) aspirin, 4-325mg tablets, if all else fails. Incidentally, since starting LDN (4.5mg nightly), I haven't had to use aspirin to treat fatigue.